Race Cars and Motorsports

Racers,

Here is a subject that is - to me - esoteric.

The SCCA decrees that to race the MG RV8 in their "Big Bore" races the MG RV8 must be restricted by several tech specifications.

The most restrictive is - "38 mm SIR fuel induction on the 3.5 aluminum V8". It IS in the SCCA new 2008 GCR (General Competition Rulebook) - check it out.

To race with the 302 Panoz, the Mustangs & Sunbeam Tigers w/289 disp, and even the new Porshche 996 GT3 Cup Cars plus the older 350 discp. Camaro and Firebird ... the 3.5 RV 8 has strong competition, to say the least.

NOW - what is the "SCCA spec" on the newest SCCA BIG BORE RACER - "38 mm SIR fuel INDUCTION ?

SIR is "Single Inlet Restriction". In this case 38 mm Single Inlet Restriction. Any size carburetor or any fuel injection is permissable - but, there will be a single hose to the opening of the induction restricted by a 38 mm restrictor. Most racers use a headlite opening for the hose to the 38 mm restrictor somewhere near the most advantageous position to the induction port.

Advantages for the MG RV8 will be weight - 2,280 lb - at tech, after each race, with driver aboard. Fuel will weigh just short of 100lb at the start of the race - meaning the GT2 MG RV8 will weigh 2,380 at the start of the race. ( A 12 gallon fuel cell will weigh 84 llb plus the weight of the fuel cell. The lighter the fuel cell, the higher the cost, by-the way.)

Almost all other specifications on the RV 8 are unlimited, other than factory original track, wheelbase and the "general appearance" of the RV 8 on the race track. The Panoz runs 10 inch front and 11 inch rear Goodyear Racing slicks. Our team has not settled on wheel sizes, yet.

The 38 mm SIR restriction is a big obstacle in overall engine decisions. Any contributions from the gang at "The Online Journal of the British V8" will be more than much appreciated.

Phillip G

I don't understand why they require you to run at 3.5L displacement when original MG RV8s had 3.9L engines.

That said, I've been told that successful MGB GT V8 vintage racer Les Gonda runs an even later Rover engine block specially sleeved from 4.0L down to 3.5L. The later model blocks had 4 bolt mains and some other reinforcements.

My intuition is that you should seriously consider electronic fuel injection and direct ignition. MegaSquirt might be the easiest and most cost-effective architecture. There are lots of manifold and throttle body options. (In England there are some pretty exotic parts available - developed for TVR and Westfield installations - but keep in mind that they're engineered for higher displacement installations.)

Would a modified Range Rover fuel injection manifold and throttle body have any real disadvantage on a 3.5L car? The throttle butterfly on the 14CUX Rover system (and probably the factory RV8) is 65mm. Although I'm certainly no motor head, I believe I'd attack the restriction rule by having someone lathe-turn an aluminum "converging/diverging nozzle" (aka "de Laval" nozzle... In cross-section it would look sort of like an hourglass except with a longer taper on the outlet side than on the inlet side). Your required 38mm restriction would thus only exist at the center of this part. I believe there are online tools for determining the optimum taper angle down to the 38mm restriction and then back up to the 65mm (or whatever) throttle plate. The point is to minimize the turbulence and choking effect of the nozzle, compared to a simple "restrictor plate". (My experience with this sort of thing is pretty limited. Eons ago, my Formula SAE team had to run a tuned converging/diverging nozzle. In that case though, there was fuel in the airstream too since our carburetor was above the nozzle to comply with the rules.)

There may be some interesting photos in these three articles:
[www.britishv8.org]
[www.britishv8.org]
[www.britishv8.org]

Have you gotten in touch with Woody at The Wedge Shop yet? He knows a lot about building these engines.
[www.britishv8.org]



Edited 1 time(s). Last edit at 02/24/2008 01:19AM by Moderator.

I just happened to come across this part (below) in my garage this afternoon. It's the air inlet snorkle from an early nineties RangeRover. (It clamps onto the air filter housing.) It's only interesting because it shows that RangeRover 3.9 engines from the factory were breathing through a 42mm restriction.

Curtis,

That Range Rover 3.9, 42mm induction restrictor is a real eye opener.

Thank you for taking that photo and sharing it with me.

Seems like the SCCA spec 38mm restrictor on the 3.5 version would be just about what the factory would have done - i.e, with their 3.5 engines.

Thanks, again.

Phillip G

I think they are confusing the RV8 with the GTV8. They have stacked the odds against you.

I'm thinking I would use a carb if the rules allow instead of fuel injection due to the 38mm restriction rule.

Do you have a link & a page number for the amendmen? I looked thru the GCR, but I didn't find your reference.

Carl Floyd,

Thanks for the induction input.

I plan on a Holly 390 - simply because I already have a good 4 barrel manifold.

First engine for the RV 8 SCCA GT 2 car will be mild, simply because there are so many other parts to the total GT 2 project.


Check out the "FASTRACK' monthly report from SCCA (National SCCA website) Jan. '08 for the update on the last minute addition of the MGB GT V 8 and the RV 8 into GT 2. The 2008 GCR had gone to press before the SCCA Competition Racing Board had added the B GT V 8 and the RV 8. Basic specs are the 3.5 displacement, stock track and wheelbase and 2,280 lb minimum weight.

Our RV 8 project is moving along and we hope to enter several races late in 2008 - probably at Heartland Park (Topeka, KS) and Mid Am Raceways (Omaha, NE).

We would love to have you join us in the pits and will keep you up-to-date as to entries. Remember though, SCCA IS club racing , low key and we are amateurs.

Phillip G.

Look what I stumbled over today... a converging-diverging nozzle made and sold specifically for GT2 race cars:
[www.raetech.com]
(http://www.raetech.com/Restrictors/Restrictor_GT.php)

Curtis,

What a discovery !

Thank you for the find on the Raetech restrictors .

I hate the cost but I value this info and will just have to deal with the cost. Sure looks like a way to more HP.

SCCA club racing is just so expensive. And it is just amateur racing. Can you imagine doing this for profit ? NO way.

Our GT 2 RV8 project will move along and this is another detail. I just got the 390 Holly and manifold and we almost have the 3.5 engine completed. The cylinder heads are mostly courtesy of D & D Development. Forged pistons were decided on in the affirmative in order to turn RPM up above 7,000 and boy were they expensive. But we will have competitive HP in GT 2.

Again, thanks for this info pertaining to the 38 mm SIR restriction. The project moves along.

Your help and the help from the other contributors to the www.britishv8 website and forum are invaluable.

regards,

Phillip G

Guys,

Found a good Firebird T 5 transmission for the RV 8 SCCA GT 2 club racing project today.

Next week we mock it up to an old 215 Buick block to fit all the ancillaries - so many ancillaries.

Our S 10 T 5 was not good for mock up - different location for the shifter and different tail shaft - so we bit the checkbook for the firebird T 5. Pefect road racing gear ratios, now, on all 4 gears AND EVEN ON THE OVERDIRIVE ! Heartland Park road course has a 3/4 mile straight away, and the RV 8 needs the OVERDRIVE. We hope the speed gun will say 165 at the end of the straight away. (Will the brakes hold?)

By the way, we are using an old 215 Buick block for the mockup while assembling the correct Rover 3.5 for the first race. So many tricks for HP are available - how much ya' wan' a spend, how fast ya' wan' a go. D&D Development says no RPM above 6,000 without forged pistons. We now have forged pistons PLUS trick heads but no racing until we locate THE oil pan and an Accusump.
.
Anybody have a good lead on a trick road racing oil pan ?

RV8 fibreglass is our worst hurdle.

The SCCA, for road racing, says we have to have the appearance of the RV 8 on the race track

Please, help us find a source of fibreglass (flared "Sebring" type wings) for the RV 8 type body panels.

Wish us luck on a silly, quixotic quest in SCCA big bore road racing.

Phillip G

V 8 Forum Guys,

RV 8 fibreglass has been secured from the UK for the SCCA GT 2 racer - front & rear bumpers, L. & R. flared wings, L & R. headlite cowls, vented bonnet & grill. The RV 8 tail lite assemblies are the last hurdle. They are just a little different than the MG B tail lites - wider.

The fibreglass was absolutely necessary to meet the SCCA weight minumum of 2,280 lbs with driver and all fluids aboard at end-of-race tech . Our goal is an SCCA, 1,900 lb GT 2 Big Bore class, V8 MG (RV 8) race car - for some balancing chassis weight is always desired and necessary.

Please keep an eye out for rear RV 8 tail lite assemblies. They are very rare.

The US RV 8 racer is almost complete. Drivetrain is close,too

Hopefully, we will test at MAM - Mid America Raceways - near Omaha late in 2008.

Help in the pits from knowledgeable people is always appreciated.

I'll keep you informed of our progress and track day plans.

Phillip G