HP guesstimates

-
S

shobes

Well-Known Member
Joined
Sep 22, 2010
Messages
84
Reaction score
1
Location
Oconomowoc,WI
We were talking today at the shop trying to figure out where the HP will be when done with the latest changes to my engine.
1973 340 .060 over KB pistons 10.5-1 compression,stock heads 1.88 cleaned up and bowl blended,Comp XE274 cam, Air gap RPM intake,Holley 750 DP carb, MSD 6al, headers.

I'm thinking in the 380-390 HP range but let me know what you think.

****edit My bad on the piston number, I have the build sheet(Kilpatrick's) from the prior owner and for some reason thought they were 107's, but in reality all the info I have is that it's a KB piston set.
 
Theres a problem here, you said 340 engine and KB-107 slugs, which are 360 slugs. Did you install a 3.58 crank?

Otherwise;

380 hp @ 5500
415 Tq @ 4000

I'd add another 30/35 hp and 15/20 lbs. of Tq with bowl ported heads.
 
.....Something is definately amiss........cause that would make a .100 thou over 360 piston.......ur compression wont be near that......seriously check ur piston #.....kim.........
 
I don't think that is going to crack 400hp with a XE274 and just the bowl ported 1.88 heads. Especially if it's a 340.

I'm thinking around 30 hp over 1hp/cid with the bowl ported 1.88's
 
Without doing any machine work, I could go with a set of Edelbrock closed chamber alum heads and a Comp Cam XS274S with solid lifters and upgrade to TTI headers. With the headers I might jump right to 1-7/8 for future consideration.

This combo should allow good street-ability but should be in the 425-435hp range I would think, or somewhere close.

Any thoughts/ideas?
 
shobes said:
Without doing any machine work, I could go with a set of Edelbrock closed chamber alum heads and a Comp Cam XS274S with solid lifters and upgrade to TTI headers. With the headers I might jump right to 1-7/8 for future consideration.

This combo should allow good street-ability but should be in the 425-435hp range I would think, or somewhere close.

Any thoughts/ideas?
Click to expand...

That's about the combo I run, but with a 416 stroker.

274S solid lifter
Edelbrock closed chamber head fully ported
9.9:1 compression
1 3/4" stepped TTI headers
M1 single plane
Barry Grant Silver Claw double pumper 750 cfm advertised
everthing port matched

I'd think it's about 425-435 hp. But that's with 56 more cubic inches.

It's pretty streetable. I've put 800 miles on it in about a month and a half. I've driven it in Los Angeles stop and go traffic jam. Take it to grocery strore.

The stroker soaks up the cam a little. But the single plane and carb take some smoothness at idle in gear away.
 
autoxcuda said:
That's about the combo I run, but with a 416 stroker.

274S solid lifter
Edelbrock closed chamber head fully ported
9.9:1 compression
1 3/4" stepped TTI headers
M1 single plane
Barry Grant Silver Claw double pumper 750 cfm advertised
everthing port matched

I'd think it's about 425-435 hp. But that's with 56 more cubic inches.

It's pretty streetable. I've put 800 miles on it in about a month and a half. I've driven it in Los Angeles stop and go traffic jam. Take it to grocery strore.

The stroker soaks up the cam a little. But the single plane and carb take some smoothness at idle in gear away.
Click to expand...



I would agree with Steve's above assessment; 365-375 at 5500 rpm and 410-415 torque at about 4200 rpm should be in range. The XE274 will use up a little bit of low end torque, but should still be crisp.

In comparison, my 324 with and XE268 and Speed Pro 8.8:1 pistons and stock heads with a good port job pulls right at 320 hp @5500 and 365 ft-lbs at 4000 rpm, with 34 degrees total, 18 initial and 670 holley SA with some tweaking done to it.

With that being said, your package should be more than capable of the 365-375 hp range.

Justin
 
Yeah, without putting it on a dyno it's all a guess. I will run the car next weekend and see what the first wave of improvements did, then I'll get the heads/cam/headers on it and go back to the track for another session.

Last year ran 13.9/103 with street tires and no traction. Hoping for some better times now and better yet after the next upgrade but sticking with the street tires.Next step get my 18 spline Liberty trans/Ram clutch back and in the car before Mopar Days 7/29-30 so I can run it hard with slicks. Thinking 13.0 or better should be real doable, those Liberty's are a breeze to speed shift.

I know seat of the pants dyno since I changed the carb/intake/ignition is noticeable so hoping time slips bear fruit. Good times for sure!
 
shobes said:
...Last year ran 13.9/103 with street tires and no traction...
Click to expand...

what was the full motor combination, rear axle gear that ran those times last year?

Hoping for some better times now and better yet after the next upgrade but sticking with the street tires.Next step get my 18 spline Liberty trans/Ram clutch back and in the car before Mopar Days 7/29-30 so I can run it hard with slicks. Thinking 13.0 or better should be real doable, those Liberty's are a breeze to speed shift ...
Click to expand...

What's are the changes you are making to the combo for Mopar Days on 7/29??
 
325, maybe 350.
I am running a 11.5 to 1 340 .30 over,x heads. all kinds of work done to the heads and I am around 425 horse.
 
Last year I had the same 340 except Edelbrock 650 4bbl, Edelbrock performer intake, stock ignition, 4.30 gears w/sure grip but a cruddy stock Hurst shifter.

Now I have 4.10 gears w/sure grip and a Hurst Vertigate shifter, Air Gap RPM intake, Holley 750 DP(73/80 for jets), MSD 6AL.

By Mopar days I'll have Edelbrock Alum heads, Comp Cams XS274 solid lifter cam, TTI headers w/X pipe and full exhaust. Also, I'll have my 18 spline Liberty geared 833 with a Ram clutch back in.( didn't mention above but upgraded my axles,studs and driveshaft already) That being said I plan to run 28 x 9 slicks and hope to launch hard!

With street tires my best 60' time was 2.13, come out just above idle and then mat it.

Sorry, I'll stop and try to keep this from turning too much into racing versus small block tech!
 
autoxcuda said:
That's about the combo I run, but with a 416 stroker.

274S solid lifter
Edelbrock closed chamber head fully ported
9.9:1 compression
1 3/4" stepped TTI headers
M1 single plane
Barry Grant Silver Claw double pumper 750 cfm advertised
everthing port matched

I'd think it's about 425-435 hp. But that's with 56 more cubic inches.

It's pretty streetable. I've put 800 miles on it in about a month and a half. I've driven it in Los Angeles stop and go traffic jam. Take it to grocery strore.

The stroker soaks up the cam a little. But the single plane and carb take some smoothness at idle in gear away.
Click to expand...

I think you are being too conservative with your motor's HP estimates, I'd seriously think based on strokers my friends are running that you are up in the 475-485hp at the flywheel. Then again all that matters is that it runs hard and makes you smile!:thumblef:
 
and the upgrades are what again so many by this day and ive changed this...Whats your final setup going to be?
 
74Burntorange said:
and the upgrades are what again so many by this day and ive changed this...Whats your final setup going to be?
Click to expand...

340 .060 over KB pistons, Edelbrock closed chamber alum heads w/mild porting, Comp Cams XS274s with Comp Cams Ultra Pro Magnum RR kit, Air Gap RPM intake, Holley 750 DP, MSD 6AL ignition, TTI headers with X pipe and full 3" exhaust. drive line will be alum flywheel, ram clutch w/scattershield, 18 spline Liberty shifted 833 w/Hurst Vertigate, custom driveshaft with big joints/yoke and driveshaft loop, 8-3/4 rear with Richmond 4.10 gears/Auburn sure grip,pinion snubber,Moser axles/big studs, super stock springs.
 
prolly around 320-350 to the floor if thats what everyone is going by. You already have around 300 to run 101 at 13 sec
 
shobes said:
I think you are being too conservative with your motor's HP estimates,
Click to expand...

FWIW I think AutoX is about right with his own estimate - I run a similar build - same intake, 20 cubes less, a bigger cam (XS282S) but inferior heads in a 318/390 and make ~ 415-425 FWHP
 
I'd like to see guesstimates from people that have run similar street/strip motors on engine dynos. Someone like Brian @ IMM has run similar motors.
 
I agree - engine dynos are always the best data.....I only have MPH/weight and a chassis dynon to go on.
 
Hopefully I can get a copy of my cousins dyno sheet/build sheet on the 408 he put together.
 
Here are spec's for my cousin's motor. 408 stroker Eagle crank/rods, Edelbrock magnum alum 61779 heads fully ported,KB 356 pistons 10.0-1 compression, CompCams 292H cam intalled at 108 centerline(= .534 lift), RPM Air gap intake, Road Demon 750 carb, full MSD ignition/coil/dist/wires, 1-3/4 headers.

dyno numbers were: peak HP 467 @5500 peak torque 503 @ 4500
 
shobes said:
Here are spec's for my cousin's motor. 408 stroker Eagle crank/rods, Edelbrock magnum alum 61779 heads fully ported,KB 356 pistons 10.0-1 compression, CompCams 292H cam intalled at 108 centerline(= .534 lift), RPM Air gap intake, Road Demon 750 carb, full MSD ignition/coil/dist/wires, 1-3/4 headers.

dyno numbers were: peak HP 467 @5500 peak torque 503 @ 4500
Click to expand...

Bigger cam that the XE274S. The 292H is [email protected] in/ex. Does he run 1.6 rocker to get .534 lift? It's advertised at .501"

Probably worth 20-30 HP or more? over a XE274S with [email protected] in. and [email protected] ex.
 
autoxcuda said:
Bigger cam that the XE274S. The 292H is [email protected] in/ex. Does he run 1.6 rocker to get .534 lift? It's advertised at .501"

Probably worth 20-30 HP or more? over a XE274S with [email protected] in. and [email protected] ex.
Click to expand...

Yes 1.6 Crane rockers were used. You are/were probably right with your HP estimates, I had forgotten which cam he was using and it does have a little more lift than the XE274S. My cousin has the motor in his 2450# 1963 Valiant, sob goes I'll tell ya but he hasn't taken it to the drag strip yet.
 
You must log in or register to reply here.
-

Back
Top