Disappointing Dyno Numbers -- I need advice please! I think something isn't right.

Hi guys,

Well, I talked to my man at the machine shop today. He quoted me these results from the break-in dyno session for my newly built 455. 359 peak HP at 3000 RPM and 480 ft lbs peak torque at 3200 RPM.

I was told that the engine was run to 5000 RPM only and at only about 140 degrees water temp.
I don't have the dyno print out yet or the blueprinting specs.

Below are some engine part details:

1970 455 SF block bored .035 over
Iron heads upgraded to stage 1 specs with multi angle valve job
850 CFM Quadrajet - Level 3 Build (Quadrajet Power)
TA 290-94H Camshaft [TABLE="width: 100%"]
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[TD="width: 100%, colspan: 4"]455H.491"-226'/.502"-235',112'
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Wiseco Forged Pistons pt055h4 see http://www.mooreautomotive.com/wiseco/wiseco-pistons-pro-tru-series/pt055h4/i-589146.aspx
Oiling mods
OEM Iron Intake
OEM exhaust manifolds

I expected at least 400 HP. Was I dreaming? Does this seem right? I know I haven't provided the blueprinting info here yet and hence have not calculated static or dynamic compression.

What questions do I need to ask to make sure that things have been done correctly? From what I understand, I need to know deck height, piston to head clearance, head gasket thickness. What else do I need to check out?

Thank you very much for your input. I want to be prepared and armed with the proper information I need for when I talk to the machine shop again tomorrow.
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<tbody>[TR="class: spec"]
[TD="class: spec_name"][/TD]
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Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

Is the HP by chance at 5000 rpm?
Which carb? Any tuning adjustments?
A printout with corrections and BSFC's would be helpful (as you've stated).
I guess I would be calm and talk to them. Their input will be very valuable.

Even if you ask the right questions, how will you ascertain things were done correctly?
Was there a goal discussed?
At face value, it appears just.
They might have stingy correction #'s or conservative tuning.

I guess specs and output should really have been planned before completion, as well as course of action and who pays for the time needed to keep going.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

I can say the intake and exhaust are holding power back. Slap some headers and ede intake on. I will bet that will get you right up there. Maybe a good tuning would help to. What is your static compression btw?

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

Before the build, I said that this would be a street-driven motor and that I was looking for 10:1 compression and approx. 450 HP. Carb is 850 QJ build to Level 3 specs by Mark at Quadrajet Power.

They might have said HP at 5000. I was a little stunned when he told me the numbers, it was 6:30am and I was late for work, so I am not sure!

I realize now that I should have had more explicit discussions along the way re: specs. I am hoping it is a case of conservative tuning and correction #'s

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

I will be putting headers on once I get the engine back here to NZ. (they are ready and waiting in the garage) Yep, also thinking I need to get an Eddy intake too.

I am not sure of my static compression as of this moment. We discussed 10:1 in the beginning of the build.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

Did they spec everything, including head flow?
I can see being disappointed nearly 100 hp down.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

I am expecting specs for everything. I don't have it yet. I am hoping to get it tomorrow.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

I meant before the build, when the decisions that determine the outcome happen.
Maybe they have a plan to improve or was this a one shot thing?
Even if they are unfamiliar with BBB's, a skillful shop being paid to verify and ascertain things should be able to hit a mark if given the right parts/info.

I'm having trouble understanding, but it seems like there's a huge miscommunication somewhere...
There can still be a huge discrepancy in power with similar 'on paper' builds.
That and dyno procedures can really differ.
This might be an extremely strong build, IDK.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

I hear ya. I need to have an in depth discussion with them. The shop (IDM Speed and Machine) has appeared very detail oriented and up front about things.

Maybe it is just about needing a good tune and headers and I will be close to where I want to be.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

What valve springs were used?
What was the installed height?

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

TA_1435
400-430-455 Stage 1 Valve Springs .500 Lift

I will inquire about installed height. Thanks for that.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

Sure that wasn't average HP? Because peak HP below peak TQ doesn't happen and certainly not peak HP at 3000k rpm,...I would however consider 400hp to be unlikely with that combo, headers won't be worth but just a few HP on that combo as well, nor would an intake to be honest, you basically built a Stage 1 and they make around 375hp stone stock

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

I think you have the numbers backwards!
torque numbers will always peak in rpm before your HP numbers do!!!

You need to get your hands on the dyno sheet, and the fact that the dyno pull was not done to atleast 5500 leaves me scratching my head, as you need the Torque and HP numbers at the 5252 rpm crossover point!

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

I was thinking the same thing as hugger, it's basicly a few cubic over stk with a cam just a touch over stock. And agree that peak ho below peak torque sounds odd. Remember that hp is calculated, torque is measured. Hp is torque over time / 5252. The time is rpm. Given your peak torque and rpm gives you 292 hp at 3200. So there is no way you lost 60hp in just 200 rpm. Something is not right with your peak hp or the rpm it's at.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

If you are wanting 400 hp at 5000 rpm you need to have 421 torque at 5000. At 5500 you need 382 torque. At 6000 you need 351.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

Hopefully you can get your hands on the dyno sheet to take a look at it yourself...specifically, check out the BSFC. I had a dyno run that produced similar numbers when using a leaner mix. We (THEY) swapped out the rods to add more fuel, and the numbers were back in the 400+ hp range. Hopefully you get to see the build specs as well so you can calculate your CR.

Also, based on what I've seen here from researching, compared to shorty headers and an aftermarket dual plane intake...your OEM intake & exhaust manifolds are NOT the culprit.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

We have come to expect HP numbers, as it was said you basically built a Stage 1 engine. I have seen Stage 1 valves installed in cylinder heads and flow less air than the STD valves as well as having them cleaned up, some porting with the same results. Installing pistons listed at 10:1 and not checking, having the compression ending at 9.3:1. Headers will help a bit, not sure how much the intake will do. A build as yours, the stock intake has a very good chance of keeping up just fine. With no head work it's possible this is it. Hope you find your relaying the results wrong. Years ago it took everything guys like Dave Mongeon and I could do to make 600 HP with race gas. Today folks just bolt that number together with catalog parts on pump gas. 600 hp is still an above average street build, but is obtainable for sure. If your number is correct with headers, maybe the intake and some tuning you should get closer to 400hp.

 

Re: Disappointing Dyno Numbers -- I need advice please! I think something isn't right

Didn't Hotrod or someone build an engine almost identical to this and make somewhere around 450 hp? The only real difference I see is that they used an Ed. intake and headers though his cam is slightly larger than the small TA 212 cam they used.