titeride85

I have been talking with someone at work about building a strong small block. He is trying to tell me to build a destroked 400. I was thinking of a 355 or a 400 (dont want the hassle of stroking for 383).

I know there is an ongoing debate about "destroking." I am not trying to get into that. I was wondering if someone with Desktop Dyno could run the numbers and let me know how much and where the peak torque and horsepower is with the application.

motors:
377 and 400

mods:
5.7 rods, 12cc dished Hyp. piston, Vortec heads, CompCams XE-268 cam, 1.6 roller rockers, Edelbrock RPM vortec intake, Edelbrock 750 carb, MSD HEI, Blue max 8mm spark plug wires, bosch plat. plugs, Hooker 1-5/8 shorty header, and a hooker 3" exhaust.

Drivetrain and suspension (in case anyone could do a drag simulator):
700r4, 2700 stall (i will be using a manual, but for ease of numbers), 3.42 posi, Eibach pro-kit springs, Hotchkis SFC, Spohn: torque arm, LCAs, LCA relocating kit, and KYB shocks and struts.

If anyone could give me a response so I know how the power and torque curves look, I would VERY MUCH APPRECIATE IT!

Thanks in advance.

88TPI406GTA

Don't go with a 377 unless you plan to be over 6000 rpm a lot. Build the 406 because more cubes is always better, unless you are looking for a cheaper way for higher RPM's.

The torque of a 406 with 5.7 rods will make you happier over the long run.

Good luck.

gtabadboy

Destroking will have your car revving at higher RPMs. It all comes down to how much money you have. I would not destroke, alot of circle track guys do this to kind of cheat I hear. I am actually making my final decisions this week to build a monster 383. On desktop dyno it is producing about 580 HP and 523 lbs of torque. If you go with the 383 you can get the best of everything or you can cut corners and build a 400. The horsepower all depnds on the $$. Id go with the 383 and get some good products and nitrous. The motor Im building will easily get me deep into the 11s with gears and a stall without nitrous.

titeride85

I appreciate the feedback, but could someone give me a side by side comparison of the motors I asked about? I want to see which motor will make more overall power and in what rpm range. Then I will know which is a better set-up. I am pretty darn sure the 400 will make more power but I need numbers if I want to prove to ol' dude at work that the 377 is pointless for the street application.

Thanks again.

Sitting Bull

Go to this thread from a few days ago and look up the DD2000 workup of a 377.

https://www.thirdgen.org/techbb2/sho...hreadid=116140

I think you'll very surprised

gtabadboy

The 400 will not necessarily make more horsepower. It just may be easier to make the HP. The 350 block is stronger than a 400 unless you buy a new block. Why a 377? Go with a 383 stroker or bore it over .060 for a 388. The engine that I am building next week desktop dynoed at 580 HP and 523 lbs of torque. It will probably bump up more when I port match the intake to heads but my torque will drop 10 lbs. It should definately rip into the 11s with the right rear end and stall. If you have any questions about my combo feel free to email me at gtabadboy@aol.com. The longblock will run you about 5500 assembled with all the best or high quality parts. I found some good prices on rotating assemblies too.l

wingnut

The Comp Cams XE-268 is a relatively mild cam. It is intended for good low-mid RPM torque. That being said, the 400 will definitely have the advantage over the 377 in this application. The 377 might have the advantage if you were planning on running a radical cam and revving the engine to 7000+ RPM.

Here are the theoretical dyno results for the 400 with your specs:

RPM/TQ/HP
1500/363/104
2000/406/155
2500/426/203
3000/446/255
3500/456/304
4000/454/346
4500/451/386
5000/424/404
5500/380/398
6000/331/378

Here are the results with the same specs accept for the shorter (3.48") stroke crank:

RPM/TQ/HP
1500/338/96.7
2000/376/143
2500/396/189
3000/414/237
3500/425/283
4000/425/324
4500/424/364
5000/416/396
5500/386/405
6000/345/395

wingnut

To show the advantage of the de-stroked 400 at higher RPM, I used your baseline engine and bumped the cam up to a Comp Cams XE-294. To accommodate the higher lift and better match the cams power range, I used Dart Sportsman II head specs.

Theoretical dyno results for the 400:

RPM/TQ/HP
2500/403/192
3000/424/242
3500/441/294
4000/441/336
4500/445/382
5000/443/422
5500/411/430
6000/368/421
6500/313/388
7000/267/356

Results with the shorter (3.48") stroke crank:

RPM/TQ/HP
2500/374/178
3000/396/226
3500/413/276
4000/411/313
4500/413/354
5000/422/401
5500/411/431
6000/379/433
6500/339/419
7000/289/385

Sitting Bull

Here is a 377 mock up, in case you didn't look. Check out that torque!!!

AJ_92RS

SittingBull,

First error is you used AFR heads. He said he was gonna use Vortec heads.

Second error is that I've never seen a set of AFR heads with 1.94" intake valves and 1.5" exhaust valves.

Third error is you used a 350 standard bore block with a 400 crank. The 377 that he's wanting to know about is a 400 block bored .030" over, and use a 350 crank.

Fourth error is TPI. He doesn't say he wants to use TPI.

Fifth error is if you read the User Manual that came with DD2000, then you would have read the using the "Roller" selection on the cam should only be used with solid roller cams. The frictional gains from using a roller cam is not a large enough variable for them to be able to use in that program.

Unfortunelty the computer I'm on right now doesn't have DD2000 on it. But I do have it at home. I'll try and get it done for you ASAP.

AJ

HrdRockA4305

Hey, where are you guys getting the patches to use specific parts on a given motor? (especially the cams and heads!) Mine dosen't have that...

Sitting Bull

Nah, no errors. I was just using another 377 work up I did for someone else a couple days ago to show what torque monsters these things are.

wingnut

I don't use DD2000. To be honest, I don't think it's a very accurate program. I use a program called Engine Analyzer v2.5 (bought through Summit several years ago). It cost the original owner about $100 (I have a bootleg copy).

With EA25, there is a large parts library to choose from. But the nice thing is, even if your parts aren't in the library, it allows you to input the specific details of your parts. When specifying cylinder heads, for example, you can actually input the flow numbers for your heads (along with width/height of your runners, valve sizes, etc.). It also allows for the use of forced induction (nitrous/supercharger).

I've duplicated engine buildups found in magazines on several occasions and found the software to be accurate to within a couple %.

titeride85

I just want to give a major thanx to you guys. I REALLY appreciate it. Now I can show old dude exactly what I was talking about.

I am VERY surprised at how close I was on my own "off the top of my head" estimate. I was figuring around 400hp/460tq with the 400ci. And about 400hp/420tq with the 377. D@mn close.

Thanks again!

titeride85

wingnut, could you run it with the profile of the XE-274 cam? I was also considering this cam for the extra cubes.

Thanks

wingnut

RPM/TQ/HP
1500/348/99.3
2000/391/149
2500/416/198
3000/438/250
3500/451/301
4000/450/343
4500/448/384
5000/431/410
5500/390/408
6000/344/393

HrdRockA4305

Engine Analyzer huh? I'll have to look for that. I think DD2000 is a little on the optomistic side for power sometimes. But, I do whatever it takes to get a baseline and just go from there, its fun to mess around with.

Sitting Bull

I can do most of that with DD2000, too. You just open up the cylinder head file, for instance, with Notepad and enter the flow numbers in the correct spot. Same with cams, enter the lift and timing specs and Save As to keep it for future reference

DD2000 also has nitrous, turbo and supercharging inputs--even intercooler and efficiency %s!

titeride85

wingnut, could you run the 400 combo with the XE-268 but substitue SLP 1-3/4 headers? I may pick up a set of those but want to know if they will do any good or not.

thanks

wingnut

I can't figure out what I did different this time, the TQ/HP figures for the baseline engine (with 1 5/8" headers) are slightly different than last time. Anyway, if the price is right, looks like the 1 3/4" headers are the way to go. I expected the engine to gain some top end horsepower at the expense of low end torque, but this wasn't the case.

w\ 1 5/8" headers:

RPM/TQ/HP
1500/363/104
2000/402/153
2500/422/201
3000/443/253
3500/454/302
4000/452/345
4500/449/385
5000/424/404
5500/382/400
6000/336/383

w\ 1 3/4" headers:

RPM/TQ/HP
1500/362/103
2000/402/153
2500/423/202
3000/444/254
3500/457/305
4000/454/346
4500/449/385
5000/427/407
5500/387/405
6000/344/393

88TPI406GTA

That data doesn't mesh well with the dyno data I have seen the in magazines lately...Just to let you know...

I would think this is another case showing that DD2000 is close, but not accurate...There would be more torque with 1 5/8" headers for sure...they are fine up to 450 HP.

Check the exhaust section for my thread on 450 HP and 1 5/8" headers.

HTH,

titeride85

I am just really curious about how much torque 1-5/8 headers can handle. Everyone says they are good to 450 HP but when do they start to restrict TORQUE??? I can see that the smaller headers improve torque...to a point, then you need more room for airflow again. But NOBODY seems to know...or at least tell anyone...where the torque restriction begins. I know I will gain some high end horsepower.

But will the larger headers improve the torque? I mean I am looking at around 460 lb-ft of TQ. And I am still CONSIDERING a 150HP dual stage shot of juice. So I may be looking at 600 lb-ft total...at times anyway.

Sitting Bull

Well, Lingenfelter's rule of thumb is to change over to 1 3/4 headers at 400 hp. The gain isn't great at that point--5 or 10 hp--but is worthwhile.