Resurrecting Casper

[TominMO]

180 might create some challenges.

My vote for understatement of the year! :-)

[sketchman]

He says it like, "Landing my Festiva on the moon will take a bit of extra thinking." lol

EDIT: What the actual frick!? I can't give Tom any rep either.

[bhearts]

I think you already know i dont know much about boost setups, but i had an idea so ill show my ignorance more . What if instead of making a high revving engine thats perfectly balanced you tune it so it has a nice wide powerband and only take it to 5 or 5500 rpm. Do a sequential turbo or a supercharger plus turbo and get the same power you were wanting except lower at like 4-5500rpm and dont worry as much about balancing it perfectly. Have full boost right from 1500rpm and do whatever to the intake and exhaust to get more power at lower rpms. That would be easier wouldn't it? And it would be kinda funny to beat more exotic cars in a race and tell them you didn't go over 5000rpm... Or would that not work or be productive?


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I would say yes, but you'd have to re gear the transmission for longer gears, so that 6k in third would still bring you to the same mph that 7.5 in third gear did.

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[bhearts]

250hp from higher boost should always be less stress on stuff than 250hp from higher rpm.

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[Festiver]

250hp from higher boost should always be less stress on stuff than 250hp from higher rpm.

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But isn't high rpm hp less stressful on the internals? I mean 10k with h beam rods is always suicide but isn't it easier on the engine to get peak power at 7k vs. 4-5k

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[Advancedynamix]

250hp from higher boost should always be less stress on stuff than 250hp from higher rpm.

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But isn't high rpm hp less stressful on the internals? I mean 10k with h beam rods is always suicide but isn't it easier on the engine to get peak power at 7k vs. 4-5k

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High RPM is destructive to engines that were not designed for high RPM. Most consumer car engines (except some diesel engines) designed to operate efficiently between 2 and 5 thousand rpm. In the case of a typical consumer car engine, Brian is correct. Making 250hp at 5500rpm with 21psi is much less destructive than 250hp at 8k rpm with 16psi of boost. However, this is not the case with all engines, or all situations. Take street bike engines for example. If you try to make max TQ at 5500rpm with a Hayabusa turbo engine, you'll destroy it much faster than if you pointed the boost curve closer to the 9k range and used less pressure. This is due to the internal design of the engine itself. Who's to say you can't fiddle with a thing or two and make a BP engine more like a Hayabusa engine internally?

[Advancedynamix]

I couldn't imagine going 180 in a festiva. I did 170 in my FD and it felt like it was about to fly away.

Yes, I agree. Going past 160 in a sub 2000 lb car is practically insane, but not impossible. Even my Cayman gets that queezy feeling over 170 and that car was designed to go that fast from the factory. This won't be a quick and dirty process. It'll take time and development, but I think I can get it dialed in.

Side note;
For those who have never driven a festiva with the engine moved forward and the suspension set up well, it's not even remotely the same experience as a typical festiva. The guy I sold Tweak to texted me one day and asked how fast redline was in 5th gear. That car has the tall 5th gear swap and redline is 6200 rpm. I told him, "way faster than you'll ever want to go in that car".
He replied, "my wife was surprised how smooth it was at that speed"
My stomach got butterflies. He was doing nearly 160mph with his wife in the car (both retirement age folks btw) on public roads, and it felt perfectly safe.

[azgtx]

Yes, I have been in that car at stupid speed and it felt like 75mph the whole time and the needle was buried and on it's second time around. That was down the US60 freeway, in town, and well over 100 at the bottom of the ramp. My wonder was what were the passed cars saying about a Festiva making the jump to light speed...punch it Chuey.

[scitzz]

No WAY! Charlie has a BP AND bought Casper all in one fell swoop???!?

Subbed!

[sc72]

^^^^ yes this is going to be a great read, can't wait for him to get started.

[kumalaba]

bp

I've already got an ATI balancer for it, but that's not one of the tricks, that's just common sense on a track driven BP.

oh ok i remember you posting why a b6t was far better than a bp for racing and thought you said that was the weak point in a bp. i ran barbie car 16 psi with stock e series @ 138 mph no problem with rktman ecu @16psi by my gps and the guy from cali believe ran his around 150-160mph? yall know him

[kumalaba]

Oh it was fastivab6tg25mr and i think he said he went over 150 but i cant remember. wont be long till shadetree will be done with my bpt g series aspire swap festy. i will be adding ms so hoping for 300 hp. hope you can come to madness and lmk if you still have that black hockey stripe or where i can get one. your car looks killer and jerry says the back section w no seat is very kool. i will have appx 4500 total including purchase price parts and labor in my car not bad.take care

[ryanprins13]

Resurrecting Casper

Great question!
The stock b6t has a power curve similar to what you speak of. It is great for sporty driving. However,on the race track, lots of time is wasted shifting or over revving the car past it's TQ peak.
The trick to road racing is to have power when you need it, and how you need it, without having to shift. That's why the chevy LS series of engine is so competitive. Those damn LS7 engines pull from 1500rpm to nearly 7000 rpm stock! That's hard to beat.
Now, with lightweight FWD the car must have a long and very smooth TQ curve that gradually rises. The quick tq curve, that your thinking of, which works great for daily driving with close to stock HP levels, is not optimal at 4 or 5 times the factory HP/TQ levels. When you need to put down 4 or 5 times the TQ that the car was built to take, the TQ curve must be a very gradual incline.
When every second counts, and momentum is the name of the game, I need a very wide power curve with enough low end or mid range to tug the car straight from a slide, but enough top end power to blast past a supercar without shifting gears in the straights. That's why I need RPM. With my b6t car I was hitting 141mph on the main straight at my favorite track (Wildhorse Pass Main track.) In order to beat the cars I want to beat, I'll need to hit 180mph on that same stretch.
Furthermore, balancing the engine is not the issue with the BP (or any inline 4 cylinder). Though balancing is important, all the components of a BP can be perfectly balanced and the engine will still be harmonically unstable due to its internal dimensions. Luckily, I've seen what BMW did to make street car 4 cylinder engines into formula one engines. This is what I'm going to do to the BP.

I was actually thinking of a power curve more like the LS, but i have no idea what the bp curve is like stock or what full boost at a low rpm would do to it. My brother in law is trying to build a kit he can sell for audi's- the A4 i think. Sequential turbos and he gets 30 psi at 1500 rpm around 1 second after flooring it. Tons of power right away thats what i envisioned but i realize the bp would probably react differently. He has a wot box as well so it keeps the 30psi between shifts and pulls hard at any rpm, lol. 7200rpm redline and awd. Last time i rode in it he was still having boost pressure fluctuation issues, so its not for sale yet, but its the fastest station wagon ive ever been in, lol.

Anyway, what you really need is a split diff. You wouldnt use the first couple splits on a 10 speed festiva racing but up high like 100mph+ it would be your ticket. I dont think you can do that in a transaxle but i didnt think you could do 300km/hr in a festiva either, lol.
Once your up to 140mph+ how does the steering react? Is it too quick or manageable?

[skeeters_keeper]

I was wondering where Casper went! Glad to see he's around. And Flyin has Matt's old BPt car! That was the first swapped Festy I ever rode in, spoiled me for sure!

Now, when is "someone" going to start a Techno rebuild thread..?

[Advancedynamix]

I was actually thinking of a power curve more like the LS, but i have no idea what the bp curve is like stock or what full boost at a low rpm would do to it. My brother in law is trying to build a kit he can sell for audi's- the A4 i think. Sequential turbos and he gets 30 psi at 1500 rpm around 1 second after flooring it. Tons of power right away thats what i envisioned but i realize the bp would probably react differently. He has a wot box as well so it keeps the 30psi between shifts and pulls hard at any rpm, lol. 7200rpm redline and awd. Last time i rode in it he was still having boost pressure fluctuation issues, so its not for sale yet, but its the fastest station wagon ive ever been in, lol.

Anyway, what you really need is a split diff. You wouldnt use the first couple splits on a 10 speed festiva racing but up high like 100mph+ it would be your ticket. I dont think you can do that in a transaxle but i didnt think you could do 300km/hr in a festiva either, lol.
Once your up to 140mph+ how does the steering react? Is it too quick or manageable?

A Festiva and an A4 Avant have about as much in common as a Big Wheel and a Jeep Cherokee. The Avant is a big, heavy AWD car with a very small engine. The Festiva is a tiny ultra light FWD car and with a stock BPT, it's got too much engine. If you use the same strategy to make the Audi fast on the street on a track purposed Festiva, you'll have a turd. The audi needs quick spool to get itself moving. Traction is not an issue, especially with the Avant. This is NOT the case with the Festiva.
Does this mean the Festiva is slow? Not at all. A stock B6T in a festiva with a dialed in chassis would embarrass any A4 that I've ever seen (mind you I've been tuning VW,Audi and Porsche cars since before the A4 existed.) The festiva is a masterpiece of engineering. It can put down massive amounts of TQ for it's weight, but that TQ has to be made properly.
Think of it this way, a Festiva with 180ftlbs if TQ at 4500rpm will pull dead even with a nearly 500hp Z06 Corvette. If that TQ continues to smoothly rise (so traction is not lost) to a 250ft.lb output at 7500rpm the car will be pulling several car lengths on a Z06 Corvette. If you try to make 250 ft.lb at 4500rpm you'll just spin the tires and have to lift off the throttle as the Corvette pulls away hard.
Now, life is NOT a straight line on a road coarse. Corners are more important than the straights. Corners are also where the little Festiva is a big time giant slayer. However, cornering on the absolute limit of control requires smooth and usable TQ. In a FWD car, you dive into corners fast and pull out of the apex with the TQ (otherwise you spin off the track like a top.) If your TQ is too aggressive and comes on too quickly then you lose traction and the car slides off the track. TQ is what pulls the car out of a slide, but too much will cause it to slide worse. My average speed around Wildhorse Pass Main track in my b6t Festiva was 78mph, with a top speed of 141mph. I enter a carousel corner at over 100mph and drift for close to 100 feet of the curve, using my throttle to balance the car. If I can't rely on it to hook up and be consistent, things get ugly.