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Old 11-23-2022, 01:53 AM
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Default Engine Dyno results questions

So my engine is finally done here is the combo……..
70 4 bolt main block, 461 , compression 10.2, 340 Cfm eheads,, port matched northwind intake, camshaft: 248 intake 254 exhaust 620 gross lift 112 lobe separation.

I am also running a Holley terminator x with a 1300 cfm throttle body

The engine was Dynoed with only a 750cfm carb as they didn’t have the setup to run efi on the Dyno and it made 551 hp and 555 torque at 6500 rpm

When I bought my combo from butler the parts combo was put together with the goal of 650hp so I was about 100hp shy of that

My questions is how close will I get to that with my 1300 cfm throttle body compared to the obviously to small 750 carb?

The goal with the Dyno was only to break the engine in properly before I put it in the car which I accomplished and everything ran great! I just wanted to get your thoughts on how much HP and torque I lost with the engine being under carbed compared to what my goal is.

Thanks as always

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Old 11-23-2022, 03:40 AM
Dragncar Dragncar is offline
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I do not think a 248 @ 050 cam would make 650 HP even with the best carb. You have plenty of head for more cam too.
Maybe I am wrong, cam just seems kind of small for your goal.
I am shooting for a little past that 650HP number with a 461 but I have a lot more cam.

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Old 11-23-2022, 06:09 AM
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At 6500? Seems like something is off. That cam, especially with that carb, should have peaked way sooner.

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Old 11-23-2022, 07:27 AM
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I've built & dynoed a number of builds over the years with similar combos if not the same.
You can expect upper 500"s hp with proper CFM.

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Old 11-23-2022, 07:46 AM
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Can you post up a dyno sheet please?

The fact that you on,y made 551 hp tells me that your flat out using only using some 275 cfm out of that 340 that the heads can flow.

Your use of the 750 Carb took 25 to 30 hp off of what the motor could have made with something like a 950 cfm Carb.

I also think that your pick of Intake Manifold is a bit of a restriction and needs some Plenum work and at least a 1/2" spacer.

It would have been nice to know how much vacuum you where pulling below the Carb at the rpm of peak hp, I bet it was over 1.5 hg which is a indicator of a good size restriction.

If you where looking for big power above 5800 rpm with the duration of that Cam it's not going to happen, this all being said I bet the motor as is will be a very nice cruiser and highway stormer!

I would be very happy to just slap on your throttle body and enjoy the motor as is because your not hooking up on the street even the 550 hp your making now without sinking a very likely 4K more into the chassis and tires on the car.

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Old 11-23-2022, 08:41 AM
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"I do not think a 248 @ 050 cam would make 650 HP even with the best carb."

+2

Not enough cam for 650hp, at least based on the 455 builds I've done here in the 600-650hp level.

The last one I remember doing that made right at 650hp used CNC ported 330cfm E-heads, Victor intake, 2" spacer, HP 950 carb and 260/;260 @ .050" cam. Had a tad more compression too.........

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Old 11-23-2022, 08:58 AM
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Ya dyno sheet. It would be interesting to know what the air/fuel was at 6500 with a 750 carb.

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Old 11-23-2022, 09:52 AM
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I will agree with the others that cam is not going to make it. Comparison my 500" IA with 330cfm E heads has a 268/272@0.050 on a 112 IC 108 and was about 650 non corrected 695 corrected with a 4150 850 carb.

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Old 11-23-2022, 10:20 AM
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More compression and valve lift would have helped. Intake work and spacer can be worth good power. Small carb will be hurting it as well.
Dialed in it has to be a 600 hp plus engine all day easy.
I'm curious though was the dyno just used to do the initial break in and check for leaks etc...no real tuning was done?

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Last edited by ta man; 11-23-2022 at 10:26 AM.
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Old 11-23-2022, 10:55 AM
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engine dynos can be all over the place just like wheel dynos. the same engine will show different numbers on different dynos, lots of variables will determine the final numbers.

the numbers do seem low for that cam & heads. just as an example my 467 with stock 72cc round port E heads, 10:7, OF 236/242 cam with a ported HO intake & q-jet made ~520 hp with a fuel pump that was inadequite, & just under 580tq. a known strict dyno with no tuning to the engine, just bolted on the parts & did a few pulls while breaking it in & checking for leaks.

seems like your engine with those specs should be making a lot more hp/tq, even with a 750 carb. im sure the EFI will help, but testing the car on the track will be the best way to show the ability of the car/engine.

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Old 11-23-2022, 10:57 AM
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Really cool build and I'm surprised they spun it that high with a 750.

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Old 11-23-2022, 11:05 AM
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Quote:
Originally Posted by 25stevem View Post

Your use of the 750 Carb took 25 to 30 hp off of what the motor could have made with something like a 950 cfm Carb.

Isn't this comment an entire waste of time not knowing the details of the 750?

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Old 11-23-2022, 11:13 AM
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Thank you so much for all the feedback guys!

Yes, the purpose of the Dyno session was just to check for leaks and get the rings seated no tuning was done at all because of the carb.

But good to hear when dialed in correctly I can hope to get over that 600 mark at least haha

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Old 11-23-2022, 12:30 PM
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Well it could be a waste of time I guess, but I was assuming that since the Op had a 1300 throttle body that was not used in that test that he would have also posted up if the 750 had seen rework to increase its cfm.

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Old 11-23-2022, 12:34 PM
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Did they give you any AFR data? It had to be super lean pulling it that high.

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Old 11-23-2022, 12:45 PM
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If the dyno had the type of Carb air hat that could measure cfm, then it would have been known in the blink of a eye if at any rpm point the Carb was trimming off needed cfm.

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Old 11-23-2022, 12:50 PM
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Just fwiw, I made 620+hp with 243 duration. I'm sure 650hp can be made with 248 duration but things need to be right

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Old 11-23-2022, 03:12 PM
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Posting a dyno sheet would really help.

That said here is a WAG. Note even at a dyno correct = 1.0 it is not using 750 CFM.

Stan

Engine_Size_=_462.18350__-__Volumetric_Efficiency_=_0.83000
BSFC_=_0.46000__-__Air_/_Fuel_Ratio_=_13.0000__-__Blower_Pressure_=_.00
BSAC_=_5.9800__-__Barometric_Pressure_=_29.9200__-__Temperature_=_60.00

__________UnCorrected______Fuel
_RPM______HP_____Torque___lbs/hr___SCFM
_6500___552.62___446.51__254.203__721.54

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Old 11-23-2022, 04:51 PM
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Quote:
My questions is how close will I get to that with my 1300 cfm throttle body compared to the obviously to small 750 carb?
Maybe 30-35 more hp. The cam just isn’t enough. Need something in 260 range duration.

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Old 11-23-2022, 05:22 PM
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Still you’ll be very happy with 585 hp, but yeah 650 be nice. Nice combo tho. Enjoy

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