Replacement race engine for Ross

[Ross Nicol]

Here are some pics of my engine being prepped for fitment. I would like some feedback from any of you guys who know the builder-

RPM Racing Engines
Grass valley CA
(916) 273-8890
Engine ID- 00232

This info is engraved on a black plate attatched to the rear of the RH head.
I have an extensive build sheet from RPM and it has-
Block- Ford 302 B50
Crank- Crower CA35361
Rods - Crower ML94905B
Pistons- JE 287592
Heads - Edelbrock Victor Junior
Cam - Crower 15416
CR - 10.15:1
Rather than bore you with further details I have an engine dyno sheet from Motec (known to be conservative) for 438HP @ 6800RPM and 369FtLb of torque @ 5500RPM with the 4 barrel shown in photo. Expert opinion reckons I'll get maybe 50HP more with my 8 barrel setup. Ooh can't wait to throw that at those pesky Porshes that drive away from me at the moment. This engine came out of Richard Bendell's (CEO MOTEC) Cobra Daytona which I purchased from him when he switched to Chev LS Power. I have been holding off fitting it till after the handling got sorted. That time is now.

Regards Ross

[Keith Hardy]

What carb is that Ross? Looks like one of they Nascar thangs...

[Sandy]

Keith -

It is a 4bbl throttle body. The motor was injected using a carb style manifold.

Ross are you going to dyno it with the stacks? Would be curious to see how it works vs. the current manifold.

Sandy

[Ross Nicol]

Thanks Sandy, yes it is a 4 barrel injection setup, I tricked Kieth by removing the fuel rails, makes it look like a carb. I'm going to be short of time to engine dyno with the stacks and will only be able to tune on a road dyno. I would like to engine dyno with the stacks but they also want too much money to do it.I'd rather buy a pair of slicks.Sandy you live in California,have you had any dealings with RPM race engines? I'm keen to know what their reputation is like.
Ross

[Keith Hardy]

Originally Posted by ross nicol

I tricked Kieth by removing the fuel rails, makes it look like a carb.

Dang! Fooled agin!

[Ron Earp]

Ross, I looked a bit on the internet but didn't come up with anything on them solid. Did find this piece of one of their cars (maybe):

"Friday night brought another round of Silver Dollar Speedway point action. With 34 winged 410's packing the pits John qualified the Four Seasons Roofing, RPM Racing Engines 71 with a lap of 12.226 which placed him 12th quick overall. It put John outside row two in the second heat race where he finished third to transfer into the night's 20 lap feature event."

Looked like a sprint car race result, which in the US means short wheelbase caged cars with a huge wing going around a 1/8th mile drit oval with around 600-800hp. If they build those sorts of engines they know what they are doing, probably. Click around in here you'll see pictures:

http://www.hoseheads.com/

Give them a call, that engine has a serial number I bet they can tell you a fair amount about it.

Ron

[Ross Nicol]

Thanks Ron
Looks like they build sprint car engines. We have sprint cars here too but I've never been to a meeting. They have some spectacular shunts though, seen them on tv.Good Idea I'll ring them they may remember the build considering it was for Richard.

Ross

[Ron Earp]

Hey Ross,

Ever find out anything about that motor? I'd be interested to hear the story on it. Like Sandy I'd also like to see the comparison with the single plane intake you've got on there now. I'd imagine if that intake has good runners and breathes well you might not see much improvement, and if your throttle bodies are not large enough you might see a decrease (I think I remember yours being large though, not the small ones that RL/RF had on many setups I saw). I hope you gain some power either way and are able to match the pesky Porsches.

Ron

[Ross Nicol]

Unfortunately I'll only have time to chassis dyno the new motor Ron.I've measured the throttle bores on the 4 barrel at 45mm, my 8 stack throttle bodies are away being upgraded so I can't measure however they will most likely be larger than 45mm and that's on 8 individual cylinders so I can't see the 4 barrel would be better.
Ross

[Ricky]

I may be silly but doesnt each cylinder "See" 4 x 45mm bores on the 4 barrel system on each induction stroke versus 1 x 45mm (+) bore on induction stroke on the 8 barrel system?

I thought this was why the 4 barrel system can produce potentially more power than the 8 barrel.

The 8 barrel is the ducks nuts for looks and is what I have on my RF, even though I did lose some power when I converted from my original 4 barrel / 8 injector system

Just my 02c worth.

[Ross Nicol]

That does make sense Rick as the 4 barrels open into a common plenum type opening before the intake runners. Let's see what others say. 2 of the throttle plates open partially before the other 2 start and then all 4 open together much like the old downdraught Weber I had on my Escort. It was Richard B from Motec that reckoned I'll get more from the 8 Barrel. However
I do compete against his Daytona Cobras, do I smell something?
Ross

[Sandy]

Ross -

I have not heard of RPM, but lots of small engine shops around here in California. The are North of me by I'm guessing 5 hr drive.

The Plenum will make a big difference in that instead of having a single 45mm per cyl you get effectivly more since they are 'pooled'. If you think about it worst case is 4 cylinders at the same time would have to be on the full intake stroke to be the same required CFM from the 4 BBL throttle as 4 individual 45mm stacks. Not to mention the effect of the plenum and intake pulse tuning and scavanging that the plenum intake can potentially provide. I think it has be mention on some of the weber threads about CFM requirements and IR vs Plenum manifolds. I have seen some discussion on it in some of the old racing books, and as I recall most agreed that it was a good thing (Broader torq, better drivablity, standard air filter and accssories can be used, etc)

The progressive nature is also a double bonus. The throttle body sounds like a nice one, like most holley 4bbls (mech sec) are some what progressive, i.e., all 4 bbls don't open at once. This is good for the track where we have cars that crank way more power then we can often use (Yes, I am guilty of this!) and want better throttle control.

To me the only downside is they don't look or sound as hot as the 8 ram tubes that you get with the Weber or EFI single barrel per/Cyl intakes.

I have the TWM set up for an engine but it will get running with the 4bbl Holley. But I would really like to have them both on the dyno to settle it once and for all (well, not that it really would...).

Lot's of 2 cents here for sure!

Ross looking forward to you flogging some of the snotty porsche drivers

Sandy

[Jac Mac]

For my money Ross I reckon you would be better off with the 4 hole injection assuming its properly set up. Both power and driveability wise.

Thats my $10.00 worth such is the state of the Kiwi $.

Jac Mac

[Jim c]

Maybe the air speed is higher in the 4brl than the 8 throttle bodys.
Higher air speed ,better cylinder fill ,better trq figures?.
8 trumpets look good though.

Jim