How much horsepower should I expect?

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schultec14

schultec14

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Hi, I am almost finished building a small block 408 stroker engine. I was wondering about how much horsepower and tq I should Expect to have out of it.

It has Aluminum Edelbrock performer rpm heads w/2.02's and 1.60's with pocket porting and are port matched to the edelbrock performer rpm air gap intake manifold it has.
I expect it to have around 10-10.25:1 compression
I have a nice 750 edelbrock to go on it
It has block hugger shorty headers w/ 2.5" collectors
Will be flowing through dual 2.5" exhausts with super 40's and an H pipe
It has a comp cams solid roller 268 cam kit, and it's pushing through harland sharp roller rockers.
it has KB IC745 pistons w/ moly rings and Eagle crank and I beam rods. *(how good are these rods??)*

What do you guys think? 400, 450, 500, more?
What difference would I expect if it had a street porting job done vs. just pocket porting?

Thank you,
-ANTHONY
 
schultec14 said:
Hi, I am almost finished building a small block 408 stroker engine. I was wondering about how much horsepower and tq I should Expect to have out of it.

It has Aluminum Edelbrock performer rpm heads w/2.02's and 1.60's with pocket porting and are port matched to the edelbrock performer rpm air gap intake manifold it has.
I expect it to have around 10-10.25:1 compression
I have a nice 750 edelbrock to go on it
It has block hugger shorty headers w/ 2.5" collectors
Will be flowing through dual 2.5" exhausts with super 40's and an H pipe
It has a comp cams solid roller 268 cam kit, and it's pushing through harland sharp roller rockers.
it has KB IC745 pistons w/ moly rings and Eagle crank and I beam rods. *(how good are these rods??)*

What do you guys think? 400, 450, 500, more?
What difference would I expect if it had a street porting job done vs. just pocket porting?

Thank you,
-ANTHONY
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Plenty of cubes, decent heads and compression but the exhaust system (block huggers and flowmasters) will cost some power. Likewise the carb over a well set-up Holley. That is a really mild roller cam you have there so its going to push out some serious bottom end torque.

Peak power might make 450 with 500TQ if not more.

As for the Eagle rods, I had some but heard the horror stories so moved them on in favour of Scats. No 1st hand experience of them good or bad.
 
Subsitute a Holley 950 for the Eddy 750 and your horsepower will increase....

I agree..the shorty headers will cost ya...
 
400 to 425 HP. Carb and headers holding you back some.

For all the money you spend on the valvetrain (rockers/roller cam), get a better carb. But the Edelbrock carb will probably have good drivability.
 
Thank you for all of your responses.

I did forget to mention this will be a street and a seldom strip car its going into.
It will have a built A518 auto, 2500 stall with 3.55 gears for now..

For the exhaust; I did have long tube headers with 3" collectors on it before, (and I still have them) but I am tired of getting a flattened pipe at the bottom... with the car at normal(or above) height with 215 70R 15s all around.. (I'm changing the rims out for stock rallye's and normal size BF goodrich tires, so it might be a tad lower than before..)What else are my options for exhaust as far as headers and ground clearance issues go? And do I lose horsepower for using the super 40's vs. anything else? Is having 2.5" pipe hurting me over using 3"? I have a set of electric exhaust cutouts on the way too if that would help my exhaust flow problem any..

For the Carburetor: As far as that goes, could I really street it with a holley 950? And is the 750 really too small? any more specific carbs to look up for my application? Would the same size holley carb make make more hp's than the edelbrock I have? (It has been jetted up 1 or maybe 2 steps from what it came off of before if i'm not mistaken)

Cam: with the trans having the 2500 stall, would it be pushing it to put the 274 solid roller in there? comp calls for 2800 stall for that cam...

Heads: If I did have a street port additionally done to the heads, how much more HPs would I expect from that?

Rods: Are the SIR rods bad for 450-500hp? (max rpm: around 6500)
 
if you do a search of the eddy 750...you will find it is a very unlike carb...with people having problems...

go with an eddy 800 AVS...thunder series for street car...

also...more info you provide easier it is to figure things out..
 
I did forget to mention this will be a street and a seldom strip car its going into.
It will have a built A518 auto, 2500 stall with 3.55 gears for now..
Click to expand...

I wouldn't change a thing.

Street car, with lots of bottom end torque, will be much more fun then one with 100 more HP.......

Port the heads, better carb, better headers,BIGger cam, HIGHer stall.............
Now you have a much faster car...........that you don't drive much because it eats to much of that high priced fuel!!!!!!

JMO:thumrigh:
 
IMHO, even with the bigger/racier carb and headers it's probably a 425-450 HP motor.

BTW that's a lot! It will fry those 215/70/15 tires at will with 3.55 and low gearset in the 518 trans. You're just loosing a little HP with carb and exhaust.

The Comp 268 roller: 268/274, 230/236 @.050, .552/.564", and 110°

Should be nice and street friendly with a 4" stroke and 230/236 @.050. And you are getting up there on lift for the Edelbrock head valvesprings. And it should idle down with an auto around 750-800 rpm.
 
Since it's a street car, I disagree with going with a 950HP. I have 2 Eddy 650 carbs that I've never had problems with (1 on my barracuda, and the other was on the 318 in my duster before I swapped it out.) I have no experience with the Eddy 750, but if it's like the 650, it should work good on a street car if that's what you already have. If you don't already have the carb, get a Holley. I stayed away from Holley for years, but realized that they aren't as difficult as I thought before. The rods should be good for what you're doing. Should be a good torquey street motor...probably low to mid 400's in HP and high 400's in TQ.
 
70aarcuda said:
Subsitute a Holley 950 for the Eddy 750 and your horsepower will increase....

I agree..the shorty headers will cost ya...
Click to expand...


yea but he's in England with $7 a gallon gas or close to it, I would keep the eddy--it idle a bit better also and hold its tune and you can adjust the a/f without dumping that expensive fuel...changing metering rods and springs beats holley jets and power valves

if your drag racing then its another story.
 
dodge freak said:
yea but he's in England with $7 a gallon gas or close to it, I would keep the eddy--it idle a bit better also and hold its tune and you can adjust the a/f without dumping that expensive fuel...changing metering rods and springs beats holley jets and power valves

if your drag racing then its another story.
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the original poster is in New Jersey.....LOL

Dude...You must be Drunk....
 
[quoteFor the exhaust; I did have long tube headers with 3" collectors on it before, (and I still have them) but I am tired of getting a flattened pipe at the bottom... with the car at normal(or above) height with 215 70R 15s all around..][/quote]


with all the money in the car already why not just get a set of dougs or tti headers. no more hitting the ground and they are full length.


.
 
You did say that you have the carb and headers already. I say use what you have and see how it runs. Spend some time dialing in the advance curve and timing and carburetor. I think your combo sounds pretty good and is enough to destroy the tires at will. The bigger parts some are recommending would add more power but the carb will cost plenty of money, the long tube headers will cause you headachs as you already know and if you run what you have first you will have a baseline to compare any changes you make. I've put bigger and supposedly better parts on some of my cars in the past and lost power, so if I had'nt had the smaller parts in the first place, how would I know? Use what you have.
 
I forgot to say my power estimate. My guess is 420 to 440 with about 500 tq. Like I said your rear tires will be begging for mercy. Also the A-518 has a .69 O/D so with 3.55 gears your final drive will be 2.45. Your cruise RPM onthe highway will be nice and low which is another good reason to keep the small parts you have.
 
I've made 530 with the 280R roller. But that was with more head and carb. I think for what you currently have, it will be fine. I think you'd do better with more more camshaft (230 at .050 is very small for the stroke, but the head are also a bottleneck), and a bit more carb. I run the Street Avenger 870VS on the 4" street engines with very good results in terms of power and mileage. Apples to apples that would be a 950+ cfm Edelbrock...lol. The smaller carb will work, but I think it's a little mismatch there. As built, it's fine, but there's a lot more in that shortblock for changes later.
 
I think i would just keep what you have! Throw it together and see how it runs! The carb and headers can be changed a later date if needed. Sounds like a good strong running engine to me.
 
schultec14 said:
Well as far as the headers go, I did find a link to a pair, but it says it wont fit with the 727 transmission?? It is also a column shift automatic.. Is there a different part number id need? ( What will the HP difference be in these vs. the shorty block huggers? )

http://cgi.ebay.com/ebaymotors/Doug...Q5fTruckQ5fPartsQ5fAccessories#ht_1361wt_1167
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I would say they would make 5-10hp more. This is a safe guesstimate from me. The TTI would prolly make more because they are a stepped header. The dougs are only a 1 5/8. Your paying for better clearance and fitting. Same with TTI paying for better fitting and Clearance, but...they are stepped to 1 3/4 and will make a little more power/Tq
 
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