Tonner on the dyno...

[TK]

Workshop ute just got tuned..

388 cube holden

308 red motor block
cut & shut 400 chev crank
stock 350 chev rods
hypatec cast pistons
HQ cast iron heads 1.94 & 1.6 valves
Smallish Crow flat tappet mechanical cam
YT rollers
Torque power single plane intake
950HP holley
Crane HI6 ignition

3000 TCE stall
Turbo 350
3.5 geared LSD 9"

258 RWKW at 6000rpm (344 RWHP)
Figuring on 35% drivetrain loss that is approx 350KW (470HP) at the motor.
Yeee-Haaar!
Not bad for a shitter engine.

Makes the drive to work more interesting.

TK

[Grumpy Rooster]

I love it when "slap together" engines totally exceed expectations.

Well done. Now you just have to run it down the quarter.

[Jim]

damn good result! well done!

[THE ASH]

um, v8 noob here - cut & shut crank?

[2JZR31]

Nice one!

Pics of car and engine bay

[BigMuz]

Excellent.

Post the graph!

Cut and shut is to adapt a chevy crank to holden rear flange and maybe front spigot so you can use a stock balancer and flywheel/ flexplate. Too much work for normal people who just buy a crankshaft rebuilders stroker crank :D

[Zac]

That's pretty stout. Take it you sorted out the fuel system?

[TK]

[ATTACH]27452[/ATTACH]
[ATTACH]27453[/ATTACH]

Photo off my phone is all I've got - not real good.
This run was done with full length twin 2 1/2" exhaust & 4 mufflers, air cleaner and pump fuel with no octane booster.
With the pipes dropped, a can of octane booster and some more timing 500HP would be on the cards.

Fuel system is sorted, no sign of lean out on the dyno.

Torque with the small port heads is massive, wheelspin on throttle application at any speed up to 80kmh.

I'll be running it down the big black dyno as soon as Adelaide has one available! (Fuck BJ, what a cunt).

I would never even consider using a cut & shut crank on a customer engine, or the stock chev rods, but it should stay in one peice for street & occasional drag use.
The bare long engine was built mostly from parts I had laying around, only new parts are pistons, rings, bearings, gaskets, cam, valve springs & sump.
Total cost (to me) was $1800.
Engine is built properly, it's just built from some fairly average parts.
Unfortunately I ended up spending another $4500 on driveline, fuel system & ignition - but it was worth it.

Cheer
TK

[XAC15T]

Very nice!

Well done mate

[gtrboyy]

Very nice!

Well done mate

x2

[SLO78U]

x3
for a poor bogan ute.........

[gtrsoon]

carbs a bit big

[BigMuz]

carbs a bit big

Good post.

numbnuts...

[ox!gen]

isn't that carb a little on the large side?

[jmac]

To be honest I don't think it is too big. There's certainly a focus on avoiding too big a carb. Let me put it this way. If you are _at all_ unsure about how to proceed, then definitely err on the smaller side. You'll miss out on a little up top but have a much easier time getting the fuel curve right and having a fantastic mid range (and still decent top end). The bigger the carb is, the more time you have to spend (and possibly _need_ to go to annular boosters or something even more exotic than the holley made ones) to get enough signal strength and produce an appropriate fuel curve.

If you look on the net, there's some advice from holley and others that suggests you mutliply engine capacity by rpm by rough estimation of volumetic efficiency and get your cfm needs from there. That 'sortof' works but it's definitely aimed for the vast majority of us who don't eat and sleep engines all day and night.

The 'trick' as to why that's not quite right is not the formula itself (that actually makes perfect sense) it's actually how the carbs are flow tested. When you look at a carb's cfm rating, it's been flow tested at a particular pressure drop or vacuum. If the engine _actually_ had that much vac at full throttle and peak torque rpms or above, then the carb itself will act as a restriction. A street driven only , or two car, you'd leave well enough alone, but a serious competition engine (which this is in a sense, even though TK is being modest about it) the engine builder would have a fit if it had that much vac at full noise. Generally speaking you want only just barely enough prssure drop in the inlet manifold to allow you to get the fuel curve spot on across the rpm range the engine optimally operates in. As a general rule you can look towards half the pressure drop as the 4 barrels are actually rated at.

Now if we retested a 950 cfm carb at the pressure drop it's _Actually seeing_ in a particular engine, you'd find it actually flows somewhat less. And not surprisingly it actually ends up supporting the engine size times cfm time volumetric efficiency estimate calculations a hell of a lot closer.

A friend of mine is running an 830cfm holley on a 308. It started life as an 850, and has much more sensitive boosters in it. It's got efi spec heads and a torquepower dual plane. The cam isn't 'massive' and it works exceptionally well with a 2500rpm convertor. And it's as close to spot on as we could get it. It definitely wasn't as quick (as also verified by some time on a dyno) with a tweaked 750 holley. Now this is just a std stroke 308. the dual plane inlet does generally need a little more cfm but still the point is made. Ideally something between the two would be perfect, but this lost nothing in the mid range, and we were looking toward a 331 combo for cheap at one point (as someone else we know was selling one)

950 might sound big, but believe me it's actually not. There _is_ still such a thing as too much carb, but you absolutely have to take into account all the variables.

TK - what pistons did you use in this if it's not a trade secret - and what was the comp height? I'm curious if there's an off the shelf sbc piston (perhaps one for a 400 crank in 350 block with long rods or something) that to suit that particular stroke (which is longer than most blokes look at with the 308. I'm also curious if you've ever done any ford cranked 308s (I"m not sure which engine it is even - something like a 352 y-block?? It's way before my time that they were done afaik)