Dissapointing Results - Have I Missed Something?

mhjo · Dec 18, 2014

Had the car in for dyno-testing and results showed 230 hp /5000 rpm (se attachement). I had expected more (of course).

Her is my engine configuration:

1. Edelbrock 500 4-port carburator

2. Edelbrock performer intake

3. Mallory distributor

4. Edelbrock performer heads

5. Comp Cams roller tip arms

6. Comp Cams roller cam
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=815&sb=0

7. Howards cams hyd roller link bar ventil lifters

8. Trickflow one piece push rods

9. HiPo manifolds

10. Dual exhaust with h-pipe and resonators

11. Dynomax VT mufflers

tos · Dec 18, 2014

Did the people performing the Dyno make any adjustments or suggestions for the low HP? I would have personally gone with a little bigger carb myself but I would think that setup would get you a minimum of 300 + HP.

Noobz347 · Dec 18, 2014

You don't happen to have a clutch that's somewhat questionable, do you?

iskwezm · Dec 18, 2014

What's your compression with those heads? When I switched from stock heads to Edelbrock I lost hp due to the bigger chambers. Carb seems small.

mhjo · Dec 18, 2014

Thanks.

1. I asked about the carb, but they said it was sufficiant. They did however change jets.

2. No clutch, only AOD

3. I don't know compression values

4. The heads, I was suggested +30 hp by changing heads, both here on the forum and in the shop were I bought. them.

Now I only need suggestions to improve the setup.

rbohm · Dec 18, 2014

is that 230hp rear wheel hp? if so then i think you are about right for your combination. i do think that your manifolds are holding you back though for a bit more power. i can see this combo making something like 250-270 rear wheel hp.

mhjo · Dec 18, 2014

It is only 170 hp on the wheels. If you study the report attached on the first post you can see the results.

Bullitt347 · Dec 18, 2014

Hi-Po manifolds and the carb being to small are most of the problem.

rbohm · Dec 18, 2014

mhjo said:
It is only 170 hp on the wheels. If you study the report attached on the first post you can see the results.

yeah, didnt look at the report which is why i asked. then you have a tuning issue that you need to work out. i would start with compression and work from there.

mhjo · Dec 19, 2014

Thanks. As I am not a mechanic, I need to know how you deal with compression?

BTW: I posted a question to Comp Cams and asked their reccomendation for Carb, but they suggested a 500 cfm (as I already have)

Hack · Dec 19, 2014

IMO you are in the ballpark for what you have built. What are your goals?

mhjo · Dec 19, 2014

Well, just to squize out the last drop... just like everybody else on this forum I guess...

Also: I read an article were the 289 K-code and Shelby engines were compared. As I could interpret the only difference was the in the carb and intake combination, so maybe Bullit347 has a point?

rbohm · Dec 19, 2014

mhjo said:
Thanks. As I am not a mechanic, I need to know how you deal with compression?

BTW: I posted a question to Comp Cams and asked their reccomendation for Carb, but they suggested a 500 cfm (as I already have)

the first thing you need to do is determine exactly what your current compression ratio is, and work from there. since your engine is already together, you can make a few assumptions that can be corrected later if need be. the first thing you need to find is a good compression ratio calculator on the web, someone here will have a link to one.

the next thing you need to know is the combustion chamber volume. with the edelbrock heads i believe that is 60cc, but check to be sure.

most pistons are down in the bore about .002", chances are the compressed thickness of your head gasket is .053", so when you use the compression ratio calculator, you can plug those numbers in along with all the others required.

i suspect that your compression ratio is going to be around 8.5:1, and you want it to be around 10:1. once you have the compression ratio calculated, you can play with the numbers to figure out how much you need to shave off the head to get to the compression ratio you want.

mhjo said:
Well, just to squize out the last drop... just like everybody else on this forum I guess...

Also: I read an article were the 289 K-code and Shelby engines were compared. As I could interpret the only difference was the in the carb and intake combination, so maybe Bullit347 has a point?

the shelby engines also had tri-y headers as well, which also accounted for the difference in power.

rbohm · Dec 19, 2014

one more thing, did you degree the cam when it was installed? if not it might also be a source of your lack of power.

Cool Beans · Dec 19, 2014

All those returns are metric. I thought that might be the issue, but you are actually making less HP than you think:

221.1 hp (ps) = 218.07 hp

http://www.mr2ownersclub.com/converter.htm

Something simple, have you checked your firing order to make sure you don't have any crossed plug wires? I had rebuilt a 460 in my old pickup truck and crossed wires 2 & 3. The engine ran pretty good other than being a turd and a little backfire on deceleration. It took way to long to figure out what I did, and when I fixed it I could smoke the tires taking off. Are your plugs gaped correctly? Correct plugs? Is everything seated? Is your choke opening all the way? lastly, have you run it without the muffler? I read a thread on my old truck forum about a turbo muffler which didn't have a baffle completely punched out. Something like that could really choke out your motor.

You're making less power than a stock "A" code motor, which is just a 4v (480 cfm) and bump in compression I believe. . .there is something big being missed.

mhjo · Dec 20, 2014

Thanks. The engine runs very smoothly and most people think the car is very fast. I only reacted to the numbers on the sheet.

Maybe I should take it to a specialist.

woodsnake · Dec 20, 2014

Do you know where your timing is at? I would start with the basics...

mhjo · Dec 20, 2014

If you look on top of the post, I just got the car back from tuning. Timing was of course also checked.

woodsnake · Dec 21, 2014

I'm sure they checked it, but I didn't see the numbers...I also think that the carb is too small, and you might be happier with a performer RPM intake and a 650 CFM. What size exhaust pipe are you using? 2 inch? 2 1/4?

Hack · Dec 21, 2014

mhjo said:
Well, just to squize out the last drop... just like everybody else on this forum I guess...

Also: I read an article were the 289 K-code and Shelby engines were compared. As I could interpret the only difference was the in the carb and intake combination, so maybe Bullit347 has a point?

Your answer is fairly vague. Usually there are tradeoffs in power versus reliability and how well the engine idles/behaves on the street. The parts you bought (heads/intake) are basically stock replacements. They are not meant to improve performance. All the parts have to be picked out that will complement each other. For instance, huge intake ports will not help you if the heads have tiny ports. I think you are seeing that now with the performance you have. Carb and intake might help, but those heads are not designed for high performance. You also have factory cast iron exhaust manifolds limiting you.

It might be possible to improve things with one or two part changes (free flowing exhaust with long tube headers or MSD aftermarket high energy multiple spark discharge ignition comes to mind), but I’m not sure from your answer whether you want to spend that money. Your selection in parts makes me think you have exactly what you wanted. Basically a stock performing engine with some new replacement parts.

Another option is to pull the engine apart and sell what you have and then research and buy parts suited to the performance you want. You could make a lot more power if you really want to.

Dissapointing Results - Have I Missed Something?

mhjo

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