Edelbrock 340 horsepower?

Posted By: RylisPro

Edelbrock 340 horsepower? - 09/11/13 06:19 AM

I rebuilt my 340 about 3 months ago and got my car dynoed last week. First pull was best and it made 314 horsepower at 5500 rpm to the hubs & 343 ft/lbs torque

Dyno guy said the AFR's were good so it was not needed to touch the carb

My combo is a 340 bored .030 over
Edelbrock heads out of the box
Edelbrock RPM cam and RPM intake
Stock cast crank 3.31 stroke, rods, rocker arms
forged pistons 9.5 to 1 compression
hydraulic lifters
650 cfm holley double pumper
1-5/8" headers to 3" exhaust with x pipe
manual trans

I figured with 10% drive train losses that my engine is making 345 horsepower to the flywheel which is 1 hp per cubic inch. I am no engine expert or anything and am happy with the motor as its really fun on the street. Just wondering if this is typical power output with this combo?

thanks

Posted By: autoxcuda

Re: Edelbrock 340 horsepower? - 09/11/13 06:25 AM

Quote:

...

I figured with 10% drive train losses that my engine is making 345 horsepower to the flywheel which is 1 hp per cubic inch. I am no engine expert or anything and am happy with the motor as its really fun on the street. Just wondering if this is typical power output with this combo?

You'd have to post that camshafts specs for people to give and opinion of your numbers.

Why 3" exhaust with that combo? Seems a bit much.

Posted By: RylisPro

Re: Edelbrock 340 horsepower? - 09/11/13 06:34 AM

My cam specs are
http://www.edelbrock.com/automotive_new/mc/camshafts/locator.php?part_number=7177&submit=go
Camshaft: Performer RPM
Part #: #7177
Vehicle Type: CHRYSLER
Engine Application: 318-340-360 V8
RPM Range: 1500-6500
DURATION AS ADVERTISED INTAKE: 308� EXHAUST: 318�
DURATION @ .050 INTAKE: 234� EXHAUST: 244�
LIFT @ CAM (Lobe) INTAKE: 0.325" EXHAUST: 0.34"
LIFT @ VALVE INTAKE: 0.488" EXHAUST: 0.510"

I got a great deal on a stainless 3 inch exhaust and could not pass it up.
It sounds great and is actually not too loud with an X-pipe

Posted By: astrobuf

Re: Edelbrock 340 horsepower? - 09/11/13 06:47 AM

Your compression ratio is a bit low. Why did you drop it to 9.5:1? With the aluminum Edlebrock heads, 10.5:1 should have been easy.

For the CR you have, your power output is about as one would expect. Pretty conservative build from what I can tell. With just a bit more work, you could have been up closer to 400 HP and still very streetable.

Astrobuf

Posted By: 340SHORTY

Re: Edelbrock 340 horsepower? - 09/11/13 07:15 AM

Closer to

20% loss for a stick

22% for an auto

Posted By: RylisPro

Re: Edelbrock 340 horsepower? - 09/11/13 07:29 AM

Quote:

Your compression ratio is a bit low. Why did you drop it to 9.5:1? With the aluminum Edlebrock heads, 10.5:1 should have been easy.

Aha! That might explain it. The engine has the same pistons from decades ago and I'm just working with what I got. Pistons are TRW L2385's and compression might actually be 8.5 to 1 ? I think my heads are 63 cc's

Next 340 that I build will have higher compression and that Ritter aluminum block

Posted By: autoxcuda

Re: Edelbrock 340 horsepower? - 09/11/13 08:14 AM

Quote:

Your compression ratio is a bit low. Why did you drop it to 9.5:1? With the aluminum Edlebrock heads, 10.5:1 should have been easy.

For the CR you have, your power output is about as one would expect. Pretty conservative build from what I can tell. With just a bit more work, you could have been up closer to 400 HP and still very streetable.

Astrobuf

With the gas out here running 91 octane and true measured 9.5 to 10.1 with a smaller cam is realistic.

Sure it would make more HP with higher compression but he might end up dialing the timing back doing a lot of street driving in traffic in a city with true pump 91 octane.

314 wheel dyno HP at 20% drivetrain loss with a stick is 392.5 flywheel HP. Pretty close to the 400 HP number.

Posted By: RylisPro

Re: Edelbrock 340 horsepower? - 09/11/13 03:20 PM

I think on this Dynapack dyno that 10% is pretty accurate. I dynoed my S2000 on there and made 216hp +21 =237hp which is right at the factory rating. At 20% it would be at 270hp and no way a stock 4 banger would make that.

I am still happy with 345hp and a healthy engine
Next time I build, I know which areas to address
Cam, compression etc...

Posted By: dogdays

Re: Edelbrock 340 horsepower? - 09/11/13 05:24 PM

Sounds like a nicely balanced package. No need to mess it up looking for a bigger number.

R.

Posted By: astrobuf

Re: Edelbrock 340 horsepower? - 09/11/13 07:49 PM

Quote:

Quote:

Your compression ratio is a bit low. Why did you drop it to 9.5:1? With the aluminum Edlebrock heads, 10.5:1 should have been easy.

Aha! That might explain it. The engine has the same pistons from decades ago and I'm just working with what I got. Pistons are TRW L2385's and compression might actually be 8.5 to 1 ? I think my heads are 63 cc's

Next 340 that I build will have higher compression and that Ritter aluminum block

Most likely, the pistons are too far in the hole and you should have decked the block.

Astrobuf

Posted By: WO23Coronet

Re: Edelbrock 340 horsepower? - 09/11/13 08:02 PM

Sounds about right for a 340 with what you have, are the heads ported or OOTB? One more thing, I thought you were going to do a Predator headed BB awhile back?

Posted By: RylisPro

Re: Edelbrock 340 horsepower? - 09/11/13 08:04 PM

I remember when I re-assembled everything that the pistons were level with the block

Posted By: RylisPro

Re: Edelbrock 340 horsepower? - 09/11/13 08:13 PM

Quote:

Sounds about right for a 340 with what you have, are the heads ported or OOTB? One more thing, I thought you were going to do a Predator headed BB awhile back?

The heads are untouched and are out of the box

I still have all my Predator stuff but I'm getting rid of it because I'm going road racing and its overkill
I want to do an all aluminum 340 with the Ritter aluminum block. If the aluminum small block came out years ago I would never have bought the Predator setup

Posted By: Challenger 1

Re: Edelbrock 340 horsepower? - 09/11/13 08:36 PM

When I built my last 340 in 2007, I used KB-243 standard pistons and they were .029" above the deck.

Then I used the open chamber Edlebrock heads designed for the hi compression early motors. I CC the heads and had 10.4-1 compression and it runs fine on 91 octane fuel for close to 18K miles now.

IMO, I hate decking heads and blocks, I rarely have it done as it messes up your top end fit. Plus you can never put it back.

Use the right parts and don't cut the heads or block, imo.

Posted By: 383man

Re: Edelbrock 340 horsepower? - 09/12/13 01:27 AM

You normally lose more like 20% in the drivetrain. I would say you have more like 375 to the flywheel. Ron

Posted By: astrobuf

Re: Edelbrock 340 horsepower? - 09/12/13 05:17 PM

Quote:

When I built my last 340 in 2007, I used KB-243 standard pistons and they were .029" above the deck.

Then I used the open chamber Edlebrock heads designed for the hi compression early motors. I CC the heads and had 10.4-1 compression and it runs fine on 91 octane fuel for close to 18K miles now.

IMO, I hate decking heads and blocks, I rarely have it done as it messes up your top end fit. Plus you can never put it back.

Use the right parts and don't cut the heads or block, imo.

Exactly right!

Astrobuf

Posted By: SomeCarGuy

Re: Edelbrock 340 horsepower? - 09/13/13 07:00 PM

Sounds about right for what you have. The heads might have needed some touches to be perfectly as advertised anyway.