I think my mechanic is a genius

[Matt Holcomb]

I called my mechanic today to ask when I could come in and fit my rebuilt MFI pump (with his supervision). It wasn't long before John told me about the engine he has just finished for a very special rally car.

Some of you may remember me mentioning a 270bhp 2.4 that John had built a couple of years ago. This was around the time that John was rebuilding my engine, and throwing around some potential horsepower figures for it. I think some of you expressed disbelief at the idea of a 2.4 developing 270bhp -- and a 2.7 developing the same sort of power. We still don't know how much power my engine is currently developing. John thinks that with the rebuilt pump it should be over 250bhp. We'll know for sure in a couple of weeks. After building a dyno-verified 270bhp 2.4, one probably shouldn't doubt him.

And after building a dyno-verified 320bhp 3.0 using the original crankcase (the same case my previous mechanic told me to junk!) from my old 1976 2.7 (now owned proudly by Adam Chaplin) for the new engine for this multiple rally-winning 270bhp 2.4, then I think one would be pretty foolish to doubt him!

But the really scary thing is that, according to John, this 3.0 would be developing close to 350bhp with twin plug heads!

Keith Seume, how about a feature article on this guy?




Matt Holcomb
MFIWDP
PRVC
BOHICA
1974 911 Carrera 2.7 RoW
1975 Mercedes-Benz 280SE
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[CamB]

250 in your car will be fun

What is the rear wheel figure for his other engines? Say the 320hp one.

Actually I reread that and I'm sounding like a doubter...

I'll reword. I have used 1.1x (ie 9.1% transmission losses) to get from 245rwhp to 270 flywheel hp. I am curious what John uses.

[Victor]

Dunno Matt, but you better tell the old dude in the photo the batteries are in the front.

[Adam]

Matt, 320bhp? That's roughly TWICE what that crankcase used to manage...

That's some serious shove! What does that motor rev to?

[WydRyd]

320BHP-350BHP from a Naturally Aspirated 3.0

That IS some serious power, w/out forced induction!

Does John do Twin-Plugging of heads in-house?

[82SC]

I remember you mentioning he keeps many of his trade secrets to himself which is totally expected...

but I'd like to know as much as possible how he achieves this...I am one to give everyone the benefit of the doubt...but I think I would be even more impressed if I uinderstood how he did this...

are his cars set up for pure race with very wild cams?
are they running on the edge of reliability?
is it rear wheel or flywheel numbers?

Maybe he should write a engine rebuild book and make some money...

well anyways any infor from you or others who have a clues as to how this is achieved would be great...

MJ

[dd74]

I'm with 82SC. I'd as well like to know how 300hp is squeezed from a 3.0.

[Adam]

Well, I'm certainly not privvy to John's magical secrets, but I do know that he tends to prefer pretty wild cams and high revs, but the engines are built for it; shuffle-pinned cases and Ti valve springs/retainers etc.

I once heard that John Gregory had a 2.4S motor that revved to almost 9k rpm... Think of him as our Australian Bob Norwood.

[CamB]

I can't help it - I'm a little sceptical.

The local dude who does the equivalent here in NZ generally gets slightly over 100hp/litre with RSR cams, twin plug, MoTeC. The best example I know of was around 110hp/litre with the M8 MoTeC (a 370hp twin plug 3.4 with 11.X:1 p&c). This car also has TWM manifolds. Car needs race gas.

The other one I know of has right on 100hp/litre with RSR cams. This is the car:

http://www.williams.co.nz/stallion.htm

Actually, I've been offered a ride in this one on Saturday if the weather is nice. Understandably, I'm a touch excited...

These cars are all tuned and measured on the same dyno (a Dynapack hub dyno) here in Auckland, and the hub to flywheel correction factor is 1.1x (9.1% assumed transmission losses).

The reason I asked my question about the transmission correction factor is that using 1.15x (assumes 13% losses) would raise each of the flywheel dyno readings by about 5% or a not inconsiderable 14-15hp on those engines above.

Using 1.2x (assumes 17% losses) bumps it up again. The 3.4 listed above would be 404hp (and I call ass on that).

Or, my 245 rwhp ("only" S cams) would imply 294 flywheel hp with a 1.2x factor.

My point is, this is a really muddy issue. I note Juan referred to 1.2x in his post about his new motor. I think this is too high (just my opinion).

And I've heard of certain Porsche tuners using anywhere up to 1.3x (LOL - I'd have over 300hp in that case). This potentially includes Merv's (WydRyd's) tuner in Melbourne and it is possibly the same as John Gregory's (depends how many good tuners in Melbourne).

I think I might post a new message. And I want to apologise ahead of time - I'm not trying to tread on any toes, I just want to figure out what is appropriate. From my perspective, if I can use 1.15x I get better bragging rights...

Cam

[Tyson Schmidt]

The way to get big HP from little CID is to simply rev the piss out of an engine.

Big ports, big valves, radical cams, lightweight valve-train and 8500-9000 rpm will get you very high peak HP numbers.

Numbers don't tell the drivability story though. Look at the Honda S2000. 240HP from a 2.0L. But not real fun unless you're on it all the time. Great for a track car. Awful for a street car.

[Wayne 962]

Hope that's not a mag case, otherwise that motor probably has a life that can be measured in hours, not miles. The aluminum cases can handle that type of stress, but not the mag cases...

-Wayne

[Matt Holcomb]

Cam,

Calculating RWHP is no fun! In the case of John's claims, his experience makes it hard to be skeptical. Having said that, I'd be surprised if my engine was developing over 240bhp (200 RWHP!) -- as you know, I have GE-60 cams and 11.3:1 JE pistons, but apart from the EBS sports springs and Ti retainers, the (single plug) heads are standard, as is the induction system.

Wayne,

He's using the old 7R mag case from Adam Chaplin's 911, the same case I was told to junk when I owned that car! I must admit, I was shocked when he told me that he used it for this motor. He has either become senile, or the 40+ years of experience is making all this possible. Time will tell, I guess.


Matt Holcomb
MFIWDP
PRVC
BOHICA
1974 911 Carrera 2.7 RoW
1975 Mercedes-Benz 280SE
Dedicated Homepage
Engine Rebuild Homepage
Porsche Owners Gallery Profile
Pelican Gallery Profile