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Most Pump Gas HP from NA 408?

59K views 41 replies 24 participants last post by  Modular  
#1 ·
What is approximately the most horsepower I can get from a naturally aspirated 408 engine on 93 octane?

Anyone have any combos as examples? Approximate cost?
 
#6 ·
I don't have a combo yet. NOTHING. The only thing that is definite is that the car will run of pump gas and be hyd roller.

I don't care about "streetablity" besides PUMP GAS.

How much horsepower can one make from a NA 408 on PUMP GAS?? Any combo, as long as it is a hyd roller, NA and PUMP GAS.
 
#7 ·
The money spent on the heads is what will be taking you the farthest, if your a 1300-1500 dollar budget guy on the heads, expect 550-560ish, real simple, nothing dramatic, no reinventing the wheel type of setup. If you have no cylinder head budget constraints, then 600+ is achievable easily.
 
#8 ·
If you know what you are doing you can make close to 600 out of a unported TW (not the R)

Ed Curtis can guide you and it can be done cheaper than most think.

Tim
 
#11 ·
408 pump gas

Two years ago I didd A pumpgas bracket racer motor, It was a 408 stock block, SCAt crank and rods. 10.75 to one, BIG solid roller cam. He did NOT want to rev past 6800. With a 1000 CFM Demon carb, super victor, and AFR 205 heads. It made 667 HP at 6700, and 590 torque at 5200. This was all on 91 octane Chevron pump gas. It cost him 14000 doollars two years ago.

JOE SHERMAN RACING ENGINES
 
#14 ·
Depends

Cam timing, heads, pistons design all play a very large roll in it. Mine has a crank compression of 180. I have heard of guys going as high as 195-200 on 93

Tim
 
#18 ·
You have two different types of compression

With a compression tester this tells you what the actual compression in the CYL is with the valvetrain in action.

Doing the math with CC of the head. and piston, gasket ect is the other. you could build a 12-1 motor that will run well on pump gas if the cam has the correct valve events and the cranking compression is around 190-200

Tim
 
#20 ·
Go here and check out the combos -- John Kaase has won it a couple of times. His pump gas powered 403 running on 92 octane put down right around 635HP up around 6200 rpm. The engines however aren't built for outright peak HP. The competition adds HP and torque from 2500 rpm to 6500 rpm and averages the amounts. So the motors are built to optimize that number. If they were just building for most peak HP, they'd undoubtedly build them for more rpm and spin them up for higher HP readings. The NASCAR boys are making 850-900 HP out of 358 cubes on racing fuel -- so that ought to give you a range of possibilities out of 408 cubes. Here's the link to the Engine masters challenge results.... http://popularhotrodding.automotive.com/60683/0802phr-2007-jegs-engine-masters-challenge/index.html
 
#35 · (Edited)
The NASCAR boys are making 850-900 HP out of 358 cubes on racing fuel --
Michael, since when did they gain another 150-200hp on their 358's?:confused: Last I knew, most were dyno'ing in the 735-790hp range.
 
#21 ·
There was a 408 I recall put together and dunoed in a rag a few years ago that did over 750hp on gas.

So, I would say that you could do 750hp with a "streetable" n/a stroked 351w. They had BIG solid cam, AFR 225s, yada, yada.
 
#24 ·
It is all relative.

I guess the only true measure is 1/4 mile times? What about tire slippage, wind, torque converter quirks, clutch slippage..etc... do they not play into diminishing the accuracy of the 1/4 mile for calcuating hp.

What is the perfect method? I do not think it exists.

PS: The article I refer to seems quite believable...SBC guys get that and more on a regular basis. It was quite a nice piece.
 
#25 ·
You will not be able to get a good honest true answer on here just some ballpark ideas. Best thing to do is speak with a few engine builders (example: Mark O'Neal at CHP) to get a feel on what your ACTUALLY going to spend. You need to decide up front what your budget is and be honest about what your goals are with the motor.

Then once you decide who you want to build the motor through then stick with that one person don't jump all over the place and talk to 10 different people b/c everyone has different methods and ideas.
 
#28 ·
To give you an easy ballpark....500 to 650 hp is EASY as a phone call for a stroked 351w.

In a light car such as a 66....500 to 550 hp with 500ft/lbs...will be very fun to drive, and should get you into the low 11's high 10's with traction.
 
#29 ·
I'm nowhere near making the most n/a power from a pump gas 408, but I think 10.54@127 mph at 3000 lbs isn't too bad (mid 70s weather).
Smallish solid roller in the .620 lift range
Ported Canfield 192cc heads
Ported Vic Jr intake
950 ish carb
2" headers to 3" exhaust (would be fine with 1 3/4 or 1 7/8)
C4 with 4400 stall, 3.73 gears and 28" tires

This was my last 408 from last year. Current 427 has been 10.45@128 at the same weight, same heads/intake/carb/exhaust, different cam, but this was in 90 degree weather

Compression was about 10.5:1

My current 427 is 11.3:1 and ran the 10.45 on 93 chevron as well with 32 degrees of total timing.
 
#30 ·
see info in my sig. The dyno numbers and best ET were with the Tremec. I now have a C4, but the first converter was wrong. I now have a 8" Ultimate Converter Concepts installed, but haven't made it out to the track... I need a bigger TB and Mass air meter and I'm sure it would make more power. Cam is a hydraulic roller that was in a motor my buddy bought.. Overall I'm happy with what it has run, which was at 3210 lbs. with me in it.
 
#31 · (Edited)
351W based dart block 460ci 13.5-1 comp. AFR 225 heads solid roller camshaft 91 notch 3250 race wt. 10.12 @ 134 mph 696hp @ 6400 motor dyno pretty respectable for only a 1.48 60 ft. 1st time out trying to get the launch down and need to use the trans brake!should run 9.70s Im thinkin.when dialed in I use 110 pump sunoco. you would get a little lower hp with less compression for 93 octane.
 
#33 ·
This thread makes me want to sell my 347 and blower to build a 408...

Damn you guys...
 
#34 ·
if you are building something to pass tailpipe smog, will a solid roller out perform a hydraulic roller? I can see a solid roller out performing a hydraulic roller when emissions are not a concern as you can have much more room to play with the ramp rates, duration, and overlap, but with the emission constraint will a solid roller still excel?

I am wanting to build a nice N/A pump gas 408 stroker than can still make it past the tailpipe emissions test.