ALL TURBO/SUPERCHARGED TEAMS - PLEASE READ

[Charlie]

I see Z. No I don't think you're ranting yet.

I hadn't seen the latest article. But in my day (I sound old ) I only ever saw one top 5 team have a supposed 50:50 weight distribution and we kept track of that.

I hesitate to believe anything in print. I only believe stuff from the horse's mouth. I love that mags like Race Tech support and publish articles on the series. But of the half dozen articles written about our car, they've all contained big errors, stuff way out in left field. Hell for our Race tech article I was the contact and I was interviewed, so I know exactly what went down. Somehow our car ended up with a reversed cylinder head! I don't blame the writers or editors, it's just that it's tough to get it all right.

I suspect the standard answer for weight distribution would be 50:50 if you don't know for sure, or don't want to say. After all most cars are close. I'm not saying I know that but I wouldn't be suprised if those numbers aren't completely accurate.

[Frank]

THE problem...

It is hard to make a 600 cc, with a relatively short wheelbase (nimble car) and have a significant rear weight bias. It's is much easier with a stacked gearbox.

It's easy to make rear heavy POS with 1700+mm wheelbase.

Try putting a weight near your diff (or the most practical rearward position), to shift your weight distribution back, and see what happens to the acceleration times...

[rjwoods77]

Thats the issue you sign on for if you use a 4 cylinder. There are a good number of engines that would package way better that wouldnt have a huge percentage of power loss over a turbo 4 cylinder. Case in point is our clean snomobile team. They were the first ones to throw a 4 stroke turbo engine in that competition. Started with a single cylinder polaris turbo and now they run a parallel twin honda silverwing engine with a gt12 on it. Made 80 hp reliably and kicked everyones ass for like the 3rd time in the events history. The reality is it is dirt simple and they really didnt put that much work in it and it handles good. They are running a new parallel twin this year that polaris used in there watercraft and will probably smoke everyone again. I gave them the option of using our old f4i engine and they said no because it is huge, heavy and high cg. That honda silverwing engine is like 30 degrees off horizontal. So you force yourself into packaging problems depending on what motor you use. So would you trade say 20 hp for 25 less lbs in engine weight, better rear weight bias due to packaging(if that is a goal for you), and the other accumulated weight loss due to a smaller package?

[Jersey Tom]

But rob..does it SOUND good

[Chris Davin]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rob Woods:
Thats the issue you sign on for if you use a 4 cylinder. There are a good number of engines that would package way better that wouldnt have a huge percentage of power loss over a turbo 4 cylinder. Case in point is our clean snomobile team. They were the first ones to throw a 4 stroke turbo engine in that competition. Started with a single cylinder polaris turbo and now they run a parallel twin honda silverwing engine with a gt12 on it. Made 80 hp reliably and kicked everyones ass for like the 3rd time in the events history. The reality is it is dirt simple and they really didnt put that much work in it and it handles good. They are running a new parallel twin this year that polaris used in there watercraft and will probably smoke everyone again. I gave them the option of using our old f4i engine and they said no because it is huge, heavy and high cg. That honda silverwing engine is like 30 degrees off horizontal. So you force yourself into packaging problems depending on what motor you use. So would you trade say 20 hp for 25 less lbs in engine weight, better rear weight bias due to packaging(if that is a goal for you), and the other accumulated weight loss due to a smaller package? </div></BLOCKQUOTE>

I read through the Clean Snowmobile Challenge rules once - at the time they allowed 4-stroke engines up to 960 cc, forced induction optional, no restrictors, and E85 as a fuel option. I'd have to go with a turbocharged CBR954RR with dropped compression. Should be good for about 250 hp. :-D

[rjwoods77]

Tom,

The thing sounds real mean. The thing pulls a crazy wheely when it tears out of the hole. Team Industries/Bender clutch and a turbo 4 stroke gives this thing some pretty brutal low end pull that most snowmobiles can only dream of. This is with a moderate engagement rpm too. Snowmobile that nearly stands up because the track hooks and trys to rotate the nose. F'in sick.

Chris,

Those rules are a recipe for a mean ass engines. Only problem is the emissions and milage requirments. The engine they run is a 632cc with a turbo and they are doing well. The new engine is something Deussen nows about and should eb way better than that silverwing engine. I thought about running that engine sleeved to be legal just to cut down on development time but the one I have now I can carry with one arm so that is taking me in different direction. I am tellign you though.. the first person to run that maxsym engine or that aprillia engine is gunna be in hog heavy(if they can afford it) because of packaging vs power. Hahahah. Did I just come up with a new measure?

[Z]

Cam,

I don't want to hijack your thread, but the following is relevant to the "turbos give too much power" argument.

The following quotes are taken from a Racecar Engineering (June 2002) article on the Brabham BT55 designed by Gordon Murray. For you young'uns out there, Murray was a hugely successful F1 designer who went on to design the McLaren F1 supercar. Bernie Ecclestone is said to have found Murray "in a broom closet", when he took over Brabham.

------------(Note; my added emphasis below)---------

BRABHAM BT55
============
"Within the first few grands prix of 1985 Gordon Murray knew that the following season's Brabham needed to be a radical departure. ... The problem lay with the BMW engine. ... Cosworth's Keith Duckworth came to peer into the engine bay and said, 'Four cylinders and one turbo? It'll never bloody work,' or words to that effect. Yet BMW's Paul Rosche ... proved Duckworth wrong on the power front, eventually achieving something over 1400bhp in qualifying trim, the figure being the maximum BMW's dyno would register.
...
"But the packaging problems imposed by the tall, upright in-line four were, by 1985, taking their toll.
...
"Murray's daring solution was the low-line BT55, in which the BMW engine was canted over at 78 degrees...
...
"And so the low-line BT55 was born, a car which had all the ingredients to be a winner ... But in actuality the car performed wretchedly in 1986, ammassing just two world championship points. There were various reasons for its failure ... This was the first Brabham to have an all-carbon monocoque ... 'There were several small problems that didn't, in themselves, wreck the performance' says Murray. 'One was that, even with carbon, I don't think the torsional stiffness was ever good enough...'
...
"Much more serious were a basic traction problem... 'It had piss poor traction because I hadn't stopped to do the sums. Lowering the centre of gravity so much was wonderful for going around corners but I should have put two or three per cent more weight on the back axle. That would have been enough. A 10-year-old could have done the weight transfer calculation ...'
...
[Murray then left Brabham and moved to McLaren]
...
"Murray set about the 1988 [McLaren] car and a second low-line design... The result was the legendary MP4/4, a car that won 15 of the 16 grands prix in 1988... Is it fair to describe the MP4/4 as the BT55 done properly though? 'Absolutely,' says Murray... 'And we didn't get the weight distribution wrong!'

-----------------------------------------

So there you go, from the cellar to the penthouse with a few extra percent on the rear axle.

Z

[310Turbo]

Sorry guys, I can't follow the forums as closely as I would like. Thanks for all the good comments so far.

Yes, you're right. Garrett has a very tight policy on not assisting FSAE teams with matching. We believe that this presents a very challenging problem for teams to tackle and we believe this is the essence of the competition. If we simply told you what turbo to use and how to tune it, where would the challenge be? So in that respect, we keep a hands-off approach. I think that we may need to start upping our assistance wrt to oil plumbing and pressures as it seems many teams are having oil control issues. I will have to consider this point further.

As for the carbon seal turbos - correct, some teams have received carbon seal turbos. We had attempted to get these turbos for the US competition but it became cost-ineffective. If we were to sponsor teams with carbon seal turbos, we would have to cut our sponsorship to about one-half of what it is today.

As such, we approached the FSAE committee for a rules change which would help alleviate much of the oil leakage issue teams face. No word from the committee yet so we'll see what happens next.

Thanks for the good posts so far, I hope this dialog continues and that more teams chime in. I agree with the concensus so far, that new teams with short development times should stay away from forced induction until they have a solid chassis and n/a powertrain setup.

Best regards,

Cam

[Matt Gignac]

Would there be any chance of getting these seals seperately though? I understand that shipping these units from Australia (where I understand they have the carbon seals) would be quite cost-prohibitive, but it couldn't be that bad to ship them loose? Or are they not completely swappable with the stock seal?

And I don't know how well the rules committee will take to changing the rules to help teams with oil consumption issues. I think it's been discussed before, and their conclusion was that any rule change meant to make the turbo compressor not see vacuum (thus solving most leaks) would mean the turbo before the restrictor, and the potential for too much power... would be cool though.

Cheers

Matt Gignac
McGill Racing Team

[markocosic]

Shouldn't think restrictor on the turbo outlet is something the rules committee would ever agree to, but a rule change to have restrictor on the turbo inlet and the throttle on the turbo outlet /could/ solve oiling issues without allowing silly power?

Throttle closed is no problem, throttle open and no boost is no problem. The only 'issue' is when on boost and the restrictor choked. There'd be a slight vacuum, but not the very high vacuum you get on closed throttle overrun - this would probably not be enough to draw the oil past the seals, especially if you're running a drysump that's 'vacuuming' the crankcase anyway?

Even if it were to leak a little, by definition you'd be at maximum air flowrate, so any little bit of oil that did leak past wouldn't cause the slugs of blue smoke that lots of oil at low airflorates causes.

If excessive shaft speed and high exhaust backpressure from a closed wastegate is an issue then the electronic wastegate is your answer?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I agree with the concensus so far, that new teams with short development times should stay away from forced induction until they have a solid chassis and n/a powertrain setup. </div></BLOCKQUOTE>

I'd go with that too - turbos (and possibly smaller or lower (when nat asp) specific output engines to match) are by no means written off, they're just something to look at once you have the time to address the issues involved.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Garrett has a very tight policy on not assisting FSAE teams with matching. </div></BLOCKQUOTE>

I'm not so sure about that... ...none of the FSAE options are as way off the mark as a "GT0.12" or "GT1200" might be - the range on offer does give a few hints.