Race engine vs Street engine with same combo

[SpeierRacingHeads]

Thought some might find this interesting. Maybe a discussion with some dyno results. This might not be a perfect A/B test, but the heads were the same and the components.

Basic engine:
4.165 x 3.48
Both LW Scat cranks
Both Mahle pistons
Both 6.000 rods
Same oil pans

Engine 1:
Whitener 1000hp 4150 VP113 fuel
13.50 compression
Vacuum pump w/11.2"
260/268 Solid Roller
.680 at retainers
106 LSA 102 ICL
677@7300 --- 545@5400

Engine 2:
Siebert 750 4150 91 Pump gas
10.50 compression
NO Vacuum pump
231/235 Solid Roller
.550 at retainers
112 LSA 108 ICL
538@6300 --- 508@5000

I know it has holes but it as honest of a test as I could do using same parts. Same dyno..

Head flow and then through manifold/carb .200-1.000.

[PackardV8]

Thanks for sharing that very interesting comparison. The additional 140 hp from just cam and compression is more than I've have given as a WAG. Suggest a very good head/intake/carb setup to take advantage of the additional lift and duration.

[turbo camino]

What was engine #1 HP at 6300?

[SpeierRacingHeads]

What was engine #1 HP at 6300?

638

[PRH]

I’m going to guess the intake manifolds are different?

Different headers for the two tests?

I know the second combo was built for its intended application, but in terms of easy power for dyno comparisons....... it seems like there’s probably 40-50hp on the table with a different cam and possibly a manifold.

[SpeierRacingHeads]

I’m going to guess the intake manifolds are different?

Different headers for the two tests?

I know the second combo was built for its intended application, but in terms of easy power for dyno comparisons....... it seems like there’s probably 40-50hp on the table with a different cam and possibly a manifold.

Engine #1 had a Burr finished 300-110
Engine #2 had a Burr finished EFI Motown

Same headers

[PRH]

So, for a motor of that size in the 570-600hp range, is one better than the other?

Whichever it is, I would think that one plus a bigger cam should close up that hp gap quite a bit.

I’m just saying the disparity between cams seems like it would be a pretty big player in the power difference.

[RevTheory]

Looks like that head is begging for more lift on the street engine.

[SpeierRacingHeads]

So, for a motor of that size in the 570-600hp range, is one better than the other?

Whichever it is, I would think that one plus a bigger cam should close up that hp gap quite a bit.

I’m just saying the disparity between cams seems like it would be a pretty big player in the power difference.

It was more of a drag engine vs street engine. I'm sure I could have put more cam in engine#2 but it did peak where I wanted it to.

Another thing is I think they both made good power. When a head works, it works on anything.

[SpeierRacingHeads]

Looks like that head is begging for more lift on the street engine.

Yea when I started that project I was trying to package it into the OEM ECU. 6200ish was all the fuel curve it could take. But I switched to a aftermarket ECU but was dedicated to the build.

[bob460]

That street engine is the perfect street engine.........will cruise all day long and you can have real fun with a tap of the foot!! ....well done

[SpeierRacingHeads]

That street engine is the perfect street engine.........will cruise all day long and you can have real fun with a tap of the foot!! ....well done

Thanks. Yea, everyone wants a 7000 rpm street engine. lol I don't get that myself.

[RevTheory]

Thanks. Yea, everyone wants a 7000 rpm street engine. lol I don't get that myself.

I don't either. That's going to be a blast to cruise around.

[Elroy]

Induction tracts if optimized are very specific////so same tract 2 different applications in this case///which one was closer to right?////interesting discussion could follow///which engine is better for what it is?//Speirracing is it that you think heads should be the same for these 2 engines or is it a self experiment. ms113 fuel is oxy//makes some comparisons harder

[SpeierRacingHeads]

Induction tracts if optimized are very specific////so same tract 2 different applications in this case///which one was closer to right?////interesting discussion could follow///which engine is better for what it is?//Speirracing is it that you think heads should be the same for these 2 engines or is it a self experiment. ms113 fuel is oxy//makes some comparisons harder

It was a self experiment.

I will agree that induction tracts are specific.

A 23 degree is a velocity limited head. IMO, it's all about the back of the port handling the airspeed from the secondary choke being upstream. If that wasn't the case a 260cfm head wouldn't make 680hp on a 358, Super Stock engine with 172cc and 1.90in at the pinch @ 7600.