[jhein]

Graph with headers



Sheet with headers

[Formulajones]

About what I suspected

Isn't it interesting how it makes more peak torque with the manifolds? That's the same results Paul has found with multiple dyno testing.

Now you know for certain without guessing. For the difference there, I'd be running the manifolds on the car.

[jhein]

For comparison, this graph is from the motor that went on the dyno right before mine. It is a Pontiac IAII 499 cid 250 + duration/600 lift cam, Edelbrock ported round port heads, single plane intake and 850 cfm (I think) carb. Based on these results I think he has a fairly stingy dyno. He told me he thinks it's 25-30 HP on the conservative side. Based on my results, and this other motor I would think maybe even a little more than 30 hp.

[jhein]

Here's a little clip of it at idle. It's hard to hear it in the video but it has just enough lope in the idle. it has 13" vacuum at 900 RPM

https://youtube.com/shorts/N8MFWY47lmA?feature=share

[Formulajones]

Originally Posted by jhein

For comparison, this graph is from the motor that went on the dyno right before mine. It is a Pontiac IAII 499 cid 250 + duration/600 lift cam, Edelbrock ported round port heads, single plane intake and 850 cfm (I think) carb. Based on these results I think he has a fairly stingy dyno. He told me he thinks it's 25-30 HP on the conservative side. Based on my results, and this other motor I would think maybe even a little more than 30 hp.

I agree. If he takes that to the track he'll be pleasantly surprised with how it runs given the numbers.

And I think yours will be the same way. You'll be pleasantly surprised.

[jhein]

And finally, here's one of the pulls

https://youtube.com/shorts/nPoYUFIrhH0?feature=share

[PDC]

Peak TQ Manifolds is 522 @ 3600
Peak TQ Headers is 519 @ 3700-3900

But at 4,900 - Headers are making 469 TQ where manifolds are making 459 TQ.

I think I’d rather trade 3 lb/ft down low for 10 lb/ft at 5k - although the difference is something you would likely never feel or notice on the street. And the headers look to hold more TQ from 5k to 5,500 where the manifolds drop off more noticeably.

If you can find a set of headers that fit well and don’t sacrifice too much ground clearance, that seems to be the way to go?

This is a really nice engine that will be a blast to drive!

[scott70]

Maybe some people dont care but I dont want to leave a large amount of power that might be missing. If you never push your car then it probably wont matter but if we're building these engines with good flowing heads,intakes,cams and headers then we're expecting some healthy power,,,correct? Attention to detail i think means everything,,,obviously degreeing cam,,trying different timing,A/F ratio,,as we know its the whole combo working together.

[Formulajones]

Originally Posted by jhein

And finally, here's one of the pulls

https://youtube.com/shorts/nPoYUFIrhH0?feature=share

Sounds great!!

[scott70]

A dyno can be stingy but that still doesnt explain a engine built like that that peaks at 4900 -5000 rpms.

[napster]

Originally Posted by jhein

For comparison, this graph is from the motor that went on the dyno right before mine. It is a Pontiac IAII 499 cid 250 + duration/600 lift cam, Edelbrock ported round port heads, single plane intake and 850 cfm (I think) carb. Based on these results I think he has a fairly stingy dyno. He told me he thinks it's 25-30 HP on the conservative side. Based on my results, and this other motor I would think maybe even a little more than 30 hp.

I think there is something really wrong with the dyno. The 499 engine has almost the same numbers as my 496 with bad port job cast iron #16 SD heads. Also, it is running a smaller cam - 242/248/112. Numbers were 519.4 HP @ 5,200 and 578 TQ @ 4,200. My engine was on a known stingy dyno. The 499 CID engine should of blown the doors off my 496. Definitely something wrong with this dyno. The engine jhein had built should be showing better numbers. I agree with scott70.

[25stevem]

Did you confirm that the carb was opening all the way, because even with headers that vacuum reading of about -.8 says that you could use more cfm, at or above 4300 rpm, especially once those numbers get above -1.1!
At .8 your motor is now starting to work at pulling air in instead of atmospheric pressure pumping it in.

[jhein]

Originally Posted by 25stevem

Did you confirm that the carb was opening all the way, because even with headers that vacuum reading of about -.8 says that you could use more cfm, at or above 4300 rpm, especially once those numbers get above -1.1!
At .8 your motor is now starting to work at pulling air in instead of atmospheric pressure pumping it in.

Hmm. Yes, we did confirm full opening of the secondaries while I was there.

[jhein]

Originally Posted by napster

I think there is something really wrong with the dyno. The 499 engine has almost the same numbers as my 496 with bad port job cast iron #16 SD heads. Also, it is running a smaller cam - 242/248/112. Numbers were 519.4 HP @ 5,200 and 578 TQ @ 4,200. My engine was on a known stingy dyno. The 499 CID engine should of blown the doors off my 496. Definitely something wrong with this dyno. The engine jhein had built should be showing better numbers. I agree with scott70.

Well, I guess I was lucky that he had just done that motor and that I got a picture of the graph. At least it suggests the problem is the dyno, not the motor.

[OCMDGTO]

I love the stealth look on that engine! Pontiac blue with the writing ground off looks fantastic! I think a timeslip is going to surprise you. That 499" +ported heads+250° cam should be 600ish hp, so it looks like his #s were low, too.

[Cliff R]

Sadly you really can't compare your dyno number to anyone else's. If it ran well, didn't spin a bearing, leak oil or coolant, no loud tapping or knocking noises, and the oil filter was clean when you cut it open after the pulls, the engine is a success all the way around.

You could take the time to carry it to Westech and get your 515hp/560ft lbs dyno sheet for bragging rights, but that would be a couple thousand dollars of wasted funds plus your time.....IMHO.

Install it in the vehicle and unlikely you'll ever hold it anyhow without a good set of DOT's or slicks. IF you really want to know how much power it makes head over to the dragstrip, install those sticky tires and get some numbers on it. It is the ONLY way to really know IF you are making the power and if the vehicle is effectively using it......FWIW.......

[jhein]

Originally Posted by Cliff R

Sadly you really can't compare your dyno number to anyone else's. If it ran well, didn't spin a bearing, leak oil or coolant, no loud tapping or knocking noises, and the oil filter was clean when you cut it open after the pulls, the engine is a success all the way around.

You could take the time to carry it to Westech and get your 515hp/560ft lbs dyno sheet for bragging rights, but that would be a couple thousand dollars of wasted funds plus your time.....IMHO.

Install it in the vehicle and unlikely you'll ever hold it anyhow without a good set of DOT's or slicks. IF you really want to know how much power it makes head over to the dragstrip, install those sticky tires and get some numbers on it. It is the ONLY way to really know IF you are making the power and if the vehicle is effectively using it......FWIW.......

Hi Cliff. Thanks for chiming in and thanks for the advice. The motor looks great, sounds great, no leaks. Lifters are quiet. Oil filter inspection good. So other than the funky dyno numbers it seems like a solid motor and I can't wait to get it in the car.

And that's exactly what I'm gonna do. Put it in the car and run it.

BTW, should I consider the 515/560 numbers to be your estimate? Because that's kinda what I was expecting, largely based on many of your posts and dyno sheets.

Thanks.

[jhein]

Originally Posted by 25stevem

Did you confirm that the carb was opening all the way, because even with headers that vacuum reading of about -.8 says that you could use more cfm, at or above 4300 rpm, especially once those numbers get above -1.1!
At .8 your motor is now starting to work at pulling air in instead of atmospheric pressure pumping it in.

Steve, I said "Hmm" to your post because I'm not sure how much I trust anything on the dyno sheet right now.

[Stan Weiss]

Originally Posted by 25stevem

Did you confirm that the carb was opening all the way, because even with headers that vacuum reading of about -.8 says that you could use more cfm, at or above 4300 rpm, especially once those numbers get above -1.1!
At .8 your motor is now starting to work at pulling air in instead of atmospheric pressure pumping it in.

Steve,
Maybe we need a clarification here. That heading says Pan and not Manifold.

Stan

[Stan Weiss]

Originally Posted by jhein

Well, I guess I was lucky that he had just done that motor and that I got a picture of the graph. At least it suggests the problem is the dyno, not the motor.

Did you get any other printouts from these runs? If not at the top of each printout is the name of the SFD file for that run. Is it possible to get these SFD files sent to you by Email?

Stan