I currently have a pretty well running LT1 in my 94 Vette Vert. With a good launch I can click off low 12s @ just over 110 MPH.
It has home ported stock heads on it and a lingenfelter 213/219 baby camshaft. Power peaks at right around 6K RPM. I purposely built it this way to keep the driveability, torque, and sleeper factor up on it.
I am actually pretty happy with the overall power on it, but I would like to up the low end UMPH on it a bit. It really doesnt turn on until it gets over 4000 RPM. My thought was to build a 383 with the CC305 camshaft, thinking this should keep my RPM range about the same, just give me some more umph down low from the extra cubes.
So I modeled it in Dynosim. I have my current motor modeled pretty well in this program, making around 425 hp @ just under 6K, and if I do the MPH/weight math based on my 1/4 mile MPH this peak HP is just about right.
I was surprised to find if I swap all of my current bolt on parts over from my current motor to the 383 with the bigger cam that the two run nearly identically up until about 3500 RPM! Then the 383 slowly pulls away only ever besting my current 350 by about 13 ft lbs of torque at 4K RPM and 19 Hp at 6000 RPM.
I was sort of surprised at this, I thought the 383 would out torque the 350 considerably, especially in the daily driving range below 3500 RPM. This small difference in top end only seems to not make it worth it to build another motor.
So after all that background info, here is my question. Does this seem right? Or is Dynosim out to lunch on this comparo in the lower RPM range? Am I actually going to realize a much more feel able difference in daily driving?
Thanks
Roy

 

Those who know me know that I dont pay much attention to dyno numbers...I went with a 383 back in 1995 because I didnt want to spin my motor to the moon to make power and torque. Generally speaking the 383 with similar supporting parts will make the power and torque at lower rpms than that of a 350/355...This allows for lower numerically rear gears and less converter which in most cases makes for a more fun street car...Its really a personal preference as there are lots of variables in builds...and I ran the Lingenfelter 211/219 cam in my 383 for years before I switched to my current Joe Overton/Erson grind...I still recommend the LPE cam to everyone who wants to have fun on the street and the strip and still pass emissions...John was on to something with his smaller duration, higher lift stuff...

My 383 runs a weenie 226/234 .568" cam and Lingenfelter/E.B. Porting LT1 heads...Last year with a Vig 3600 and 4.10s it went the times/mph in my sig...The bottom end is all Lingenfelter and was built back in 1995 and remains untouched with 52,000 hard miles on it... The dyno numbers stink around 375 rwhp on a calibrated Mustang dyno, but its a friggin rocket ship on the street and it only needs 63-6500 rpm to get the job done..If you went by dyno numbers alone you'd laugh at my set up. Dynos are great for tuning but I cant tell you how many times I've out mph'd guys with much higher dyno numbers...

--Alan

 

With a mild setup like that if you think it is lacking torque below 4000rpms there is a problem of some sort. A cam that peaks at 6000rpms is not big enough to cause a lack of lowend unless it is spec'd rather badly.

425hp at the flywheel is pretty LOW for a heads/cam LT1.

IMO there is a LOT left in the 350 with a different topend on it and with a potential for a torque increase everywhere.

https://ls1tech.com/forums/lt1-lt4-m...s-429rwhp.html

 

I'm still a big fan of your build.

My stock cube setup with an almost identical cam only put barely 350 to the wheels through a loose stalled auto, and ran 11.7s consistantly . There are a LOT of people who overcam their stock cube and mild headed builds.

My cam for the 383 is MUCH healthier though, but its not really a street car anymore either . We'll see how it goes .

 

Hmmmm, I appreciate the info, but I am not sure I am able to garner the answer I was looking for from it. Perhaps I didnt word my question correctly or supplied too much info and it fogged it all up. I didnt mean to imply that I felt my car was lacking in the low RPM torque dept, only that I wanted more! It has plenty of torque, but like all LT1s it really comes on as the revs get up.
So lets forget my particular motor. What I am trying to figure out is the answer to this question from a more theoretical standpoint.
What I am trying to figure out is whether or not the dynosim predictiion makes any sense or not. It doesnt sem to make sense to me that if you build a 350 and a 383 with similar compression, designed to peak in the same RPM range, using the same top end parts that you should not make considerably more power below 3500 RPM with the 383. Why would the power curves be nearly identical up until 3500 RPM with the bigger motor when they make peak power at the roughly the same high RPM?
Is there a valid reason I am not seeing for this to happen? Is the smaller Lingenfelter cam just plain better than the CC305 that it creates the same low end power from the smaller cubes? Something else? Or is the Dynosim program just all washed up with its predictions at these lower RPM ranges and cant be relied upon?
Thanks
Roy

 

You are not going to like this but your problem is that you are bench racing too much.

Stoker torque is overhyped, yes a well done stroker should make more torque BUT a well done stock shortblock should have part throttle traction issues on the street so how much more torque is useable??

HP is a function of airflow not displacement, people get carried away in their quest for displacement all the time.

The 305 is not that great a cam, far as I know that is usually ground on a 114 which is a step in the wrong direction. http://www.babcox.com/editorial/ar/eb90252.htm

The Lingenfelter cams work well, ever example of their use I have seen has run respectably.

Use the cheap simulation programs for entertainment only, you don't get any meaningful information from them.

All that said a stroker can be better than stock displacement but people jump on that bandwagon too soon, at this point spending $3000+ on a shortblock wont gain you much of anything, but putting that same $3000(or less since you could reuse rockers and such) into a new topend will gain you more like 50 hp at the crank. Look at the link I posted, that is more RWHP than you have at the flywheel.

Topend makes power, without a proper topend the bottom build wont be worthwhile. Your results say there is a LOT more to be had with the 350 yet.

With the relatively low rpms the computer allows us a 350 should make great lowend.

To be clear I would like a 383, but wont do it till I can do it right, expect to spend an easy $3500+ on a good shortblock.

I know my opinion clashes with "common knowledge", most opinions and a LOT of stroker owners egos but when I can drive 500 miles and stomp on trailered stroker I think that maybe I have something figured out. The FEW strokers done well can walk all over my car but so few folks get them right, because they are more worried about displacement than topend.
With an engine like the LT1 that has a stout shortblock, spend the money on the topend first, if it were a weak bottomend then I could see doing the shortblock first and then upgrading the heads as funds permitted but that is not the case here.

 

You stomp on 383 cars with your 12.30 car?

 

12.3 was my WORST pass in 08 you know the car runs 11.9 you are just trying to throw bad data out there???

.3-6 faster than the popular stroker stuff same track same day.

 

Your car ran an 11.95 ONCE. Not twice, not all day, just once. That perfect air day, with the stars aligned, tailwind, full-moon etc. You said so yourself, i don't feel like digging through your 5000 posts to find it. A typical day at the track your car is a 12.2-12.3 car, hardly stomping a 383 car. I've seen low-buck cast crank 383 f-bods in the high 11's. I've never seen them "trailered" either. I can't imagine anyone "trailering" a high 12 second car.

 

^You need to take into consideration that his car is a full framed 4 foor sedan that can seat 6 people and has 600lbs on most F bodies. I'm sure if it weighed what an F body does it would be running mid 11s.

 

It would do that ONCE, LMAO! Then it would be a 11.90 car!

 

As a point of reference, during a supercharged engine buildup, there was some testing done with a 383 w/ CNC ported stock LT1 heads, low compression (9.25:1) in normally aspirated mode. Not exactly the optimum compression for N/A mode, but a good point of reference.

With 3.42 gears & a 2800 stall, a cc305 cam through cats & exhaust on 255 drag radials, it went 12.1's in a full option Z28. Obviously with 11:1 compression, more converter & 3.73 gears, it would have run a lot better.

With the charger installed the same combo went 10.0's still through cats.

I personally ran my 383 w/ a cc305 cam & it would pull 6th gear down to 900rpm with 3.42's with the same engine combo above.

6th gear was way more usable than when it was stock. Something to be said for that 383/cam combo relating to low end torque. Not saying it is by any means the best combo out there, but nothing to criticize either.

 

Why would I not like that? Actually I usually have a wrench in my hand and dont get to bench race as much as I would like to! But hey even I can appreciate the humor in a guy with 4600 posts telling a guy with 9 that he spends too much time bench racing.

Well, none in the lower gears, but quite a bit in the higher ones.

This is true, and maximum HP is going to be limited by maximum airflow. But all things being equal a larger displacement engine should be able to move more airflow than a smaller one at less RPM. Thereby making that same power with less revolutions.

You are probably right about that But I havent really spent too much time with these type of programs. I spend most of it with wrenches in my hand, remember? The results arent jiving with what my brain is telling me should be happening which is why I am questioning it.

There is no question that bigger power can be made by dropping cubic $$$ on something or spinning it higher. I have a 2600 lb 550 Hp AFR 210 headed monster if I need my adrenaline fix. You must also keep in mind that the flywheel HP figure for my corvette came from that for entertainment purposes only computer program, not a dyno, so it probably isnt even relevant.
But I am really not interested in big power on this particular car. What I am interested in is having it drive like stock, Idle like stock, get great gas mileage, and pull like a big block when I roll into it in 3rd or 4th gear. And cubic inches makes that easier to accomplish.
I have to build another LT1 motor for a 78 vette I am resto-modding anyhow, so to build a 383 for this car and put the one in it now in the other vette really doesnt cost me much at all.
And hey you guys, Stop hijacking my thread!

Roy

 

So Lonnie, bottom line it for me. Do you think that I would see a reasonable seat of the pants difference in the low end pull with the 383 CC305 combo vs the 350 Lingenfelter 211/219 setup?
Or maybe you or someone else has a reccomendation for a better camshaft to accomplish this goal?
Thanks
Roy

 

I use the dynosim program alot, and it has always been very accurate. I think you are seeing the truth on it, your cam/heads combo on that 350 is just that much better matched than on the 383. Have you tried using the same cam and everything and just changing the stroke?
I honestly like the short stroke 350 myself, but if your buying a new crank might as well go with the 383. I know that i have been in some 350ci LTs that will put most 383s to shame in the TQ department, its all in the setup

 

Grr, I have tried exactly that! With the Lingenfelter camshaft Dynosim shows the 383 motor making about 10 less HP than the 350 and peaking at only 5500 RPM rather than the 6000 it pulls to now. It does show about a 20 ft lb increase at the lower RPMs however, but I would hate giving away that extra 500 revs.
Roy

 

from reading and understanding how the lt1's are when i build an engine itll be a stock stroke 355 with good heads and a good cam and a very good tune. right gearing and youll see 20+ mpg highway and a very fast car.

 

My car has run 11.9s much more than once that it only did it onece is just a lie yes I am calling you and your sources liars. Like I said, slowest pass on 08 was 12.3. If you saw a post by me saying 11.9 was a one time deal then it would have been a couple years ago, because it has repeated every fall since. Actually I believe the first day it went 11.9 I made a few 11.9s you are making up lies to try and discredit me, flattering actually.

Then again if I had a car so much lighter with more spent on mods and only went .2 faster I might be bitter too.

I am comparing my car to other b-bodies. I am sure that is much too fair a comparison for a feeble minded dolt like you to accept.

 

I am not making up lies, I am just going off of my memory, sorry. Your constant brainwashing of AI stuff has scrambled my memory slightly. I dug around for a bit and I did find this from you though " Your car loses 8 tenths when the wheels get a little heavier? Hrmm....sounds odd.

I spent more on mods? Hrmm...not too sure on that. Irrelevant really, because it's not like i'm anywhere near finished with it. I'll get it into the low 11's, probably 11.2-11.3 without touching the motor. I doubt you'll have an answer for that, LMAO. I don't even give a **** if someone with a smaller cam runs faster, kudos to them. My combo isn't optimal, i've said it a million times. It still runs strong, that's all I want. My car has been to the track once just to get some baseline numbers thats all. You car is maxed out for your combo. That's all she wrote. You'll have to dive into the internals to get it faster N/A. Bitter? Me? LMAO...hardly. I could give 2 ***** what you think of my car. I NEVERpush my stuff onto anyone else unlike yourself. You'll never once hear me tell someone to run my cam. If they ask "can it be done?" i'll reply yes, but I won't recommend it. You are a broken record with the same old song and dance every time you post. I am not biased at all when it comes to other peoples car. I like seeing people try different things out just to break from the mold. You are like the jehovahs witness for AI, knocking on everyones thread telling them how wrong they are unless they "see the light" and make a carbon copy of your taxi-mobile. You mention it in about 2500 of your 5000 posts, maybe you'd take the hint and realize how annoying it is.

feeble minded dolt, LMAO! Aww...is someone upset? The internet toughguy, BWAHAHAHAHA!!!!

 

Your car runs 11.72 every time you go to the track?? summer, fall,low pressure high pressure, hot cool, humid, dry, etc.??

The 12.7 was on street tires you proved how feeble minded you are because apparently traction or lack thereof is beyond your grasp.