454 efficiency - Maximum CR

Propane, Butane, LPG, GPL, C3H8, C4H10
storm
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Re: 454 efficiency - Maximum CR

Post by storm » Sat Nov 18, 2017 11:01 pm

gottago wrote:
Sat Nov 18, 2017 10:33 pm
What cam specs would work best for the intended purpose with this weight vehicle starting with a bbc at 11:1 cr?
Basic questions get basic answers that are then spread all over the internet and taken as gospel by some and/or ridiculed by others. All they do is add to the confusion of cam choice. Because of this I don't give basic answers.
gottago wrote:
Sat Nov 18, 2017 10:33 pm
Even the basic dyno programs are way better than nothing for the generation of torque and hp charts. You can then see the changes from differing cam specs reflected on the same charts.
The vast majority of cam manufacturers and/or grinders have already done this and they create cam charts that can easily be found online which offer basic recommendations. These are basic recommendations given when people ask basic questions.

There is a thread on speedtalk where David Vizard supplies a formula for calculating cams https://speedtalk.com/forum/viewtopic.php?f=1&t=45639. Try it out and see what you come up with.
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gottago
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Re: 454 efficiency - Maximum CR

Post by gottago » Sun Nov 19, 2017 3:12 am

I have limited experience with bbc. Not many of the online sites are all that helpful with propane requirements. Any insight and suggestion from someone knowledgable in this area is helpful imo.. Even Vizard fails to differentiate between liquid and gaseous fuels. The octane charts are helpful though. Not trying to lure you into anything.. You know as much about the parameters of the projected build as I. The poster is actually asking for advice on all the details that would make this work well for his purposes. Personally, I may do a bbc in the future and would like to learn as much as possible first too..

BigBlockMopar
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Re: 454 efficiency - Maximum CR

Post by BigBlockMopar » Sun Nov 19, 2017 6:26 am

As so happens last weekend I did some more reading about the 128-camtech. Had seen it mentioned before but never looked any deeper into it.
Found the LSA of the cam I had selected for my 11:1cr 360ci build (CompCams XE256) seemed to be confirmed as fairly correct by the calculator.

Here's the online calculator to input some data in; http://www.wallaceracing.com/calc-lca-vizard.php
https://www.bigblockmopar.com
'73 Dodge Dart - 318ci - IMPCO E vaporizer / 425 mixer - A518-OD trans - 3.55 gears - 225/50/17" tires.

storm
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Re: 454 efficiency - Maximum CR

Post by storm » Sun Nov 19, 2017 1:19 pm

BigBlockMopar wrote:
Sun Nov 19, 2017 6:26 am
As so happens last weekend I did some more reading about the 128-camtech. Had seen it mentioned before but never looked any deeper into it.
Found the LSA of the cam I had selected for my 11:1cr 360ci build (CompCams XE256) seemed to be confirmed as fairly correct by the calculator.

Here's the online calculator to input some data in; http://www.wallaceracing.com/calc-lca-vizard.php
Good find, I had no idea Wallace racing added that to their calculators.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

storm
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Re: 454 efficiency - Maximum CR

Post by storm » Sun Nov 19, 2017 1:29 pm

gottago wrote:
Sun Nov 19, 2017 3:12 am
Not trying to lure you into anything.
I know your not and that isn't what this is about. The point is working of basic info will give a basic answer but this is not a basic question. If it was burb could rebuild the 454 with truck engine specs and be happy. Burb is looking for something more and to provide a good answer, not a basic answer, more information is required. As it is for a basic question my reply will be get a selection of cam charts and go from there. Forget about differences between LPG and petrol because as long as the compression suits the octane rating of the fuel (regardless of the fuel) a low to mid rpm (idle to 3500-4000 rpm) engine you are looking for a smooth idle - torque cam.

The only thing I would suggest is to go for a hydraulic roller cam if they are available.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

gottago
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Re: 454 efficiency - Maximum CR

Post by gottago » Sun Nov 19, 2017 4:24 pm

One of the reasons that I avoided the bbc was that of all the propane conversions I had seen, the bbc seemed to have more problems than the others. Heat issues, head gaskets etc.. I don't know if that was inherent or caused by the propane use. Those were likely just stock engines as well. In the big block category, Vizards cam selection process really leans to the power side, zero compensation for fuel mileage. Also its a huge huge difference driving a 105 lsa cam at 11:1 and a 112 lsa cam at 11:1 . What you can do with each is entirely different. I know some people don't put much stock in dcr as opposed static but this is where it really comes into play. The big cam companies usually advertise a recommended compression ratio for each cam. Just a quick look demonstrates how the recommended cr changes with lsa and duration.. Which leads to another basic sort of question.. When a cam company recommends say 10:1 cr for a particular cam intended to run on gasoline, what compression increase should one use to compensate for running the same cam on propane?

I'm sure there are quite a few choices that would work fine but there is probably one that suits burb's purposes better than the others. That would require a bunch more info and details. Just getting in the ballpark is more theoretical initially though. For example, the hyd roller cam.. If the bbf is of any use for comparison, it was expensive, it did up midrange power noticeably, it did not enhance fuel mileage at all, more the opposite.. That wasn't a big consideration in that build but maybe is here. Prior to the roller cam in the bbf, it once had a very low lift midrange hyd ft cam 112 lsa and rhoads lifters. The torque was excellent and the mileage at least 25% more. Was just a 4500 rpm cam as opposed the 5500 of the roller. Just mentioning some things I have run into.

storm
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Re: 454 efficiency - Maximum CR

Post by storm » Mon Nov 20, 2017 4:02 am

You make an interesting comment about Vizards choice of power against fuel mileage. In my experience any engine that is built based on well thought out requirements (i.e. realistic and suiting the purpose) is going to make max power for the purpose yet be as fuel efficient as it can be.

Power is a by product of torque, I know you know this but others may not see a connection so I'll go through it for them.

HP = Torque x RPM ÷ 5252. This means that you need torque to make HP and the Torque and HP curves cross at 5252 rpm. In order to get a heavy vehicle moving we need torque as low down as we can practically get it so this means we need a flattish torque curve from idle to a safe redline (e.g. 5000 rpm). Gearing can be used to help compensate because it can force the engine to get to the usable torque band quicker but we aren't talking about a lightweight racecar that will move quickly when the throttle is mashed so I am deliberately not thinking about higher rpm cams.

Match the cam to the engine to the car and you'll be very close to the ballpark, fit a cam that doesn't come in until 3k+rpm to an engine in a truck that will rarely see over 3.5k rpm and you'll use more fuel cause the engine will be very inefficient for the purpose it is being used for.

So ... before we go much further there are a shopping list worth of things we need to know about the engine, vehicle, and driver. If you want a basic recommendation just pick a torque cam that has an rpm range from idle to about 4k rpm.
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burbfixer
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Re: 454 efficiency - Maximum CR

Post by burbfixer » Tue Nov 21, 2017 12:29 am

Wow, thank-you guys for being interested enough to continue discussing this!
storm,
My apologies for the confusion earlier. I had the thread going over on Speedtalk and some here were posting on it, so I kinda picked up the conversation from there, but once cam entered into it, you might have been left in the dark a bit. Didn't mean to disrespect the other posters on my thread.... I do really appreciate all the input! You make a good point about a well thought out build generally does everything well, including fuel efficiency. In my limited experience, that has been my observation as well. On page 30 of the " Vizard's secret 128 cam # revealed" over on ST, someone asks him about fuel economy, and he does give an interesting answer.
In my "454 Efficiency" thread on Speedtalk I tried to give a fairly detailed description of the vehicle, it's usage and my goals for the engine. I've added more information in this thread that gives some more details about my vehicle and what I'm trying to achieve. I also did another thread over there : "Bbc daily driver cam question". The intent of that was to ask about cam sizing to enhance every aspect of a near stock engine, but not give up anything any where in the rev range. To avoid confusion and hopefully get more input, I intentionally left propane out of it, and used 87 octane gas and 8.5-9:1 as the ballpark cr. My reasoning in doing the thread that way was that I can doctor the cr in my actual build to compensate for propane's octane by about 1.5-2 points, and the consensus on the min cam sizing should still have some validity.
By the way, no one needs to worry about misleading me, I have no intentions of running to the bank with any one thing one person says. I think that's the value of this and other forums - gathering opinions, experience and consensus. But in the end, I will make my own decision about things like compression and cam, and take full responsibility for how it turns out. The input and suggestions have already helped me a great deal, and caused me to consider some changes to my combo I hadn't thought of before.
gottago,
You made a very good observation about terminology. I might be confusing others in my use of the term "low end". Midrange, if we're talking about maybe 2000-3500 or so, is where alot of around town driving is done, even with my tall gearing. I guess the reason I haven't even referred to "midrange" yet in any of my posts is because with the type of build I'm doing, I think the engine should easily have a ton of it either way. But I really like my low cruise rpm, and so need the engine to run very cleanly and efficiently as low as 12-1300 rpm. Particularly with cam choice, building in such a way that off idle and low rpm torque isn't compromised should ensure that the part throttle response is fun and that the very low cruise rpm still pulls the vehicle around fairly effortlessly.
I checked out the Wallace Racing site, and hadn't realized someone had actually done a calculator for Vizard's formula. It, and the dcr calculator, are both very cool. I"m a bit unclear about the result with the dcr calculator though. When I filled in the data for my old 396 I had to use 12.25 cr in order for the cranking compression result to jive with what I actually read on the compression gauge. Something's not right with that..... If I can get it to make sense to me, I could use the calculator to target a certain ccr result. The reason I'd be focusing on ccr is because it's a value I've actually tested on an engine I actually ran, so it gives me a real world frame of reference to work from with my current build.
By the way, not sure why you've seen so many bbc having issues with propane. Many of my friends and family used bbc's on propane, so I personally was around probably 10 or a dozen bbc's, both stock and modified, over extended periods of time, and never heard of heat or gasket issues. In my experience they were even more reliable than the sbc's - and those were awesome!

storm
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Re: 454 efficiency - Maximum CR

Post by storm » Tue Nov 21, 2017 3:14 am

No problem burb I've not had much opportunity to read or take part properly because I've been away and also trying to find a place to live.

I tend to try to get back to basics so that I am sure the person asking the question understands but more importantly, from my perspective, that others who come in months or years to come can see that the question they are thinking about asking has already been discussed and developed from a basic discussion to an indepth discussion.

Ok back to discussing cam choice. As you are aware the purpose of a cam is to provide a means for the engine to fill with air and then expel it. The word efficiency is a double edged sword that is, often, highly misunderstood. By saying it is misunderstood I mean that someone joins a forum about engines and starts talking about engine efficiency. I try to wait to see if they define what they mean by "engine efficiency" before I get to far into things. Why? because fuel efficiency is very different to volumetric efficiency which is very different to thermal efficiency etc etc etc.

Cams have a direct impact on fuel efficiency and volumetric efficiency but increasing 1 more often than not decreases the other. Volumetric efficiency increases as engine rpm increases simply because, to a certain extent, the engine is able to breath in more air at higher rpm. More air = more volume = higher volumetric efficiency. It also means more fuel is used because you need to have a certain amount of fuel to mix with the air so your fuel usage appears to increase. The only way to increase volumetric efficiency without moving the rpm range higher is to use a different type of cam. A flat tappet cam is not very efficient at enabling the engine to breath in and out, a roller cam is much better because of the increased are "under the curve".

Now lets get a little bit more technical. A cam that works well for a 454 running at idle to 4500 rpm would have a similar engine like a 396 running well at 1500- 5000 rpm.

So lets get back to exactly what you want. In your last reply you said "But I really like my low cruise rpm, and so need the engine to run very cleanly and efficiently as low as 12-1300 rpm." which indicates to me you are not really interested in "volumetric efficiency" at the expense of "fuel efficiency". I was, from the start of this thread, thinking that was your intent so my discussion has attempted to "guide" towards a torque type cam that has a range from idle to about 4500rpm. To provide a more indepth answer and to get the best fuel efficiency possible more information like cylinder head airflow specs (and intake manifold airflow specs as well if possible) would be needed.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

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gottago
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Re: 454 efficiency - Maximum CR

Post by gottago » Tue Nov 21, 2017 11:24 pm

Hey a discussion!! Eventually a few cam choices will surface. Gotta agree with what was said about establishing a bit of background info for everyone to work with and see from..

as far as..
You made a very good observation about terminology. I might be confusing others in my use of the term "low end". Midrange, if we're talking about maybe 2000-3500 or so, is where alot of around town driving is done, even with my tall gearing.
I checked out the Wallace Racing site, and hadn't realized someone had actually done a calculator for Vizard's formula. It, and the dcr calculator, are both very cool. I"m a bit unclear about the result with the dcr calculator though. When I filled in the data for my old 396 I had to use 12.25 cr in order for the cranking compression result to jive with what I actually read on the compression gauge. Something's not right with that..... If I can get it to make sense to me, I could use the calculator to target a certain ccr result. The reason I'd be focusing on ccr is because it's a value I've actually tested on an engine I actually ran, so it gives me a real world frame of reference to work from with my current build.
By the way, not sure why you've seen so many bbc having issues with propane. Many of my friends and family used bbc's on propane, so I personally was around probably 10 or a dozen bbc's, both stock and modified, over extended periods of time, and never heard of heat or gasket issues. In my experience they were even more reliable than the sbc's - and those were awesome!
Burb, you have portrayed your expectations quite well now.. I even get it.. The clicker for me was when you described flooring the engine you have in your suburban for the first time. I am just getting old enough now to appreciate certain engine characteristics other than the all out power side. I am a slow learner in that regard, I don't think I've ever owned a vehicle that I haven't wound out no matter what it was. One does have to remember that we don't all drive the same or want the same..

In regard the low end. From what I have seen all the modern torque cams really do create torque especially in combination with higher compression. A big cube engine can easily get into the too much zone if you don't watch for it. But they can be very responsive and have a fun side, paying attention to gearing is a must. The 700r4 transmission has a very low first to get things moving.. It can also break things.
I"m a bit unclear about the result with the dcr calculator though. When I filled in the data for my old 396 I had to use 12.25 cr in order for the cranking compression result to jive with what I actually read on the compression gauge. Something's not right with that..... If I can get it to make sense to me, I could use the calculator to target a certain ccr result. The reason I'd be focusing on ccr is because it's a value I've actually tested on an engine I actually ran, so it gives me a real world frame of reference to work from with my current build.
That is a good approach, I like to feel the results of the theoretical before I actually believe. I just meant for that calculator to demonstrate the static cr link to dcr and cranking pressure. Change the intake close point in seat to seat duration, not 50 thou specs if that is what happened. You do need the real numbers off the cam card. Advance or retard position of cam changes the ivc too which changes the results. Its good to understand where you've been before going to the next.. Keep playing with that stuff til you get it to match real world results. The next will be more predictable.

As far my experience bbc well that may be a bit misleading.. Our family owned a service station back when gov subsidies were available for propane conversions. We were near a big dam project where money was flowing. In the narrow segment of years I was around that business, there may have been a lot more gm trucks than fords being used in that area in those years. I recall one bbc head in particular being the suspected culprit. These were mostly all heavy use work type trucks and included the odd motorhome and camper. So it may just be my experience which had some extreme use and coincidental factors that I should have considered. But that is where it began. I have a brother running the 454 now. 200,000 miles on it, pulls like a freight train. Not apples to apples though, he changed to a 6 speed trans and it is a heavy work truck. But it rekindled an interest.

So OK, cam choice.. Should be done with an eye to making the entire package work together.. A cam range, a compression range, a head choice, intake man etc.. To match burb's driving style..
Do a quick test on Vizards formula.. I'm pretty sure that is close to max torque but would you want to drive that? What could be done to tame it enough and for the mileage to improve? hmmm

gottago
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Re: 454 efficiency - Maximum CR

Post by gottago » Thu Nov 23, 2017 4:56 pm

Even after getting it narrowed down to a cam range, there are still multiple ways to skin the cat. Recent post on speed talk from camking.... shorter exhaust duration equals more midrange but tops off earlier..

Where to install the icl can change things a fair bit too. The racers are doing a cam drill, (advance retard the install point of the cam) on a dyno. I doubt burb wants to go there so as close as possible right off the bat required.

The closest running condition I know of to what burb desires was in a 408 ford.. Higher compression, low duration, square duration, medium low lift cam.. 112 lsa. Quite an experienced fellow.. ran it for years installed straight up. It did sign off quite quickly. Then retarded the cam an extra 4 degrees. Did not loose any bottom end but gave it way more range. Now cruises the coquihalla highway effortlessly and with an added 2 mpg.. Not a bad thing to keep in mind.. Even a few small changes can make the difference.

burbfixer
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Re: 454 efficiency - Maximum CR

Post by burbfixer » Sun Dec 03, 2017 2:30 am

First off, Still totally appreciate the input from all of you, and it's kinda cool to be hearing things from one guy who must live within 2 or 3 hours from me, another who's down in Australia, and another from Netherlands. Gotta love the internet for that!
BigBlockMopar,
It sounds like there are several similarities in our goals with our engines, so thanks for your input. Glad the 128 calculator worked for you. That's a 212/218 cam isn't it? Likely not far off from the cam I'll end up choosing. It appears I may end up with a touch more duration as per CamKing's recommendation over on ST, but I still need to email him to get exact numbers for my lpg combo.
Storm,
Good points about the different types of efficiency.
I undertand that to make specific recommendations, more information is required about my exact combo, but honestly, I'm just getting some of those questions sorted out at this point. I do have a stock Gen V 454 sitting on the floor of my garage, and I do plan to install it in my Suburban. But I'm not in a hurry - the 350 in my vehicle runs fine. Maybe by spring/summmer the 454 will be ready to install. Honestly, if this were an engine already in a vehicle I was driving, I'd probably just be concentrating on externals like intake, exhaust, and tuning, and living with the 7.something compression and whatever cam is in there. Since it's easy to work on the internals now though, I want to improve the compression and camshaft timing to better suit the fuel and the intended usage in my vehicle. Optimizing, or as close as possible, those two things, compression and cam, were the real basis for my inquiries on this and the other forum, and I've benefitted greatly from the input I've recieved.
I will likely use the stock peanut port heads, and do some minor pocket porting, or possibly use some L29 Vortec heads. Internet info is the closest I'm ever going to get to knowing the airflow of these 2 possible heads, but it appears they each flow about 235-240 cfm @.5 on the intake and about 180 cfm @.5 on the exhaust. As far as the intake, there are several possible directions I could go, but one thing I'm strongly considering is giving the engine 2 mixers. Logic is telling me that because of the design of air-gas valve style mixers, there should be no downside at low rpm, but the added airflow potential would improve midrange and upper rpm power, maybe dramatically. I may also consider a roller instead of a flat tappet cam.

Gottago,
I have gone to wot many times with my current setup, especially when doing tuning runs out on the hiway, I just hadn't done it from a dead stop yet. (I'm definitely getting older and mellower with my driving habits, but I'm not dead yet!) Interesting info about adjusting cam timing. Wouldn't have guessed it would be such a dramatic difference, but that's why this hobby isn't boring...
Your own engine combo sounds very, very impressive. That's kinda the holy grail - an engine that pulls hard everywhere, gets great fuel economy, and revs to 7000! You, and others, have caused me to re-consider if all-out low end torque should really be my highest priority. I can still have my great low cruise, but do all the rest better too. I respect diesel type power, but it's not exactly what I want either - otherwise I'd be planning a 6.2 turbo, or a cummins swap. I found a thread on Team Chevelle where Cam King was chiming in and he said some interesting things about going too small with cam choice - and it fits well with what you've been recommending. Sorta the same as the compression thing - safe and conservative is fine, but too conservative isn't. With cams he says there's a point where any smaller becomes counter productive - even at lower rpm ranges, and evidently, that point is not as small as I would have guessed. I may end up e-mailing Jones Cams with all my info and letting him build my cam - he seems very knowlegeable, and it sounds like he has propane experience too.

BigBlockMopar
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Re: 454 efficiency - Maximum CR

Post by BigBlockMopar » Sun Dec 03, 2017 6:24 am

Correct on the 212/218 specs at .050 for my cam.
I chose the cam purely on duration (good vacuum at idle for powerbrakes) and listed rpm operating range.
1.6 rockers were used on the cam to give it a tad more lift.

I'm curious where your cam specs end up.
https://www.bigblockmopar.com
'73 Dodge Dart - 318ci - IMPCO E vaporizer / 425 mixer - A518-OD trans - 3.55 gears - 225/50/17" tires.

gottago
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Re: 454 efficiency - Maximum CR

Post by gottago » Tue Dec 05, 2017 8:45 pm

I have gone to wot many times with my current setup, especially when doing tuning runs out on the hiway, I just hadn't done it from a dead stop yet. (I'm definitely getting older and mellower with my driving habits, but I'm not dead yet!)
Sorry about that comment lol.. didn't mean to impune all that.. I think you are well on your way now to being able to put together a nice package. Decide on heads and valve /port size and do check out the tunnel ram or similar choices. Get the compression ratio right for the cam selection and it should feel pretty darn good. Cam king is definitely a guy worth checking in with. Side note on my latest cam, it is a square pattern and although it has 230 degress duration @50 it is only a 277 duration cam at seat to seat. ( Howards cam) There is quite a difference in ramp rates etc in modern cams and they will all act a bit differently. I really like the midrange concentration of power that I got from this. I did retard the cam and could mainly due the square pattern thus shorter exhaust.

The dual 4 tunnel ram has other benefits beside getting two mixers, it also straightens the flow to the front and rear cylinders and equalizes the length in the already longer intake runners for an increase in the torque at lower rpm. Some of the results gained I am thinking are somewhat of a propane thing.. The flow and the compression work well together on my combo with a relatively low lift. I've gone the other way in other builds, upping the lift and dropping duration. I wasn't as happy with fuel mileage going that way. I am just relaying my own experience in regard fuel mileage and that from less than a dozen vehicles since I really began taking note of those changes. Hah, I must be getting old too!

ps.. link to some calculators and some basic cam info ..
includes David Vizards overlap recommendations.. I run at the top end of his daily driver recommendations / 54 degrees overlap but doing so with added compression.. Its a number worth keeping track off during cam/ compression considerations.. Mike Jones will want you to have all your parts figured out and most all the compression and flow values known before he will give real specific cam recommendations.

burbfixer
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Re: 454 efficiency - Maximum CR

Post by burbfixer » Thu Dec 07, 2017 1:12 am

Oh, no worries at all, you've been awesome! I thought the impression I'd given was kinda funny, that's all. Thought I should clarify. Nowadays, I tend to drive with awareness of the "fusible links' in the stock drivetrain. With my 77 Stepside, the supercharged 396 & 44" tires tested things to the limits, and I broke stuff....alot at times. Changing axles, ujoints, gears, etc was almost fun then, but anymore, mmmm not so much. Funny how priorities change.
I'm curious about the 377. That's a 400 block with a 350 crank, correct? Why that and not a 400? For the rpm capability? That cam is definitely high intensity! But the camshaft mysteries continue for me... I'd never have guessed a 230 @50 cam would be a good 'mileage' cam under any circumstances! What's that engine in? What's the cruise rpm where the mileage is so good?
The info on this forum has taken it to a new level, but my interest in tunnel rams had been increasing since the Roadkill/Engine Masters guys have been using them and explaining the benefits. Plus in his latest BBC book Vizard promotes them as a top choice if you can make the room for it. It makes sense that it should work - long straight runners, big plenum (which they say propane likes), 2 mixers. Do you find the cold start crank times acceptable on yours?

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