Blueman33

I am not looking for the explaination of why a turbo has to spool up, but an explanation of why today's technology of 'no lag' can't be applied to our cars.

I have a car similar to stock 951 in engine size and output. GT Cruiser which has 215 hp with 2.4 ltr engine. It hits boost when you hit the pedal, there is no turbo lag at all.

I think I read a post about a turbo eclipse saying they also have virtually no lag.

What is it about the PT Cruiser Turbo that allows instantaneous spool up and why can't the technology be applied to 951???

Kurt

I like the turbo lag! For one, you can drive around town without boost, saving gas when needed. Two, it's that addicting feeling when you're thrown back into the seat that I love.

My favorite quote in regards to this:
It's not turbo lag, it's foreplay

It deals more with how they integrate the turbo into the engine's rpm band. Typical customers of modern turbocharged cars don't want a raw, rough acceleration - but rather a nice smooth acceleration as if it wasn't turbocharged.

Sam Lin

Blueman33, you hit the nail on the head - GT Cruiser doesn't make 260hp, and try upping the boost - the small turbo runs out of flow.

Try comparing to the WRX - 2.5L, similar output, similar lag.

Sam

turbo951fan

Yes, you can probably find a turbo for our cars with much less lag, but the HP numbers are very limited.

EZRider

I think you can apply today's technology on our cars. It's just a matter of priority and how you plan to use your car. There are hundreds of turbo combinations to choose from. The sky is the limit if you can pay for it

porshhhh951

it completely depends on the size of the engine and the size of the turbo. Different turbo's on different appilcation's spool up differently. Our car's in stock form don't have much lag. Every car is different. Think of it this way typically the faster the turbo spool's the more chance it has of running outta gas up top. Lag in some respect is a good thing cause that means you are running a decent size turbo with decent boost pressure. The chances of you holding all of your boost to redline are better than most.

I am sure some of the real tech guy's will chime is with the mathematics of it.

mumzer

its my opinion that the biggest single issue (all other things being equal) is the amount of plumbing between the exhaust port and teh turbine housing.

a great part of the exhaust energy that would otherwise be turning the wheel is lost through radiation and expansion in the crossover.

put a pyrometer on the primary tube at the head and then take a read at the pipe just below the turbo at idle.

we ran garretts with .73 AR and larger hot sides on 2.5 litre ford (yes the pinot motor) in transam mustangs and merkurs and were constanlty struggling with wheelspin at low rpm and part throttle...it was no coincidence that these motors mounted the turbo about 12 inches from the exhaust port.


just an opionion....but if you are using waste heat to drive a turbine, a design that allows 30% of that heat to escape before the rubine housing aint exactly genius.

toddk911

"but if you are using waste heat to drive a turbine, a design that allows 30% of that heat to escape before the rubine housing aint exactly genius."

So what could we do to combat this on our cars??

epbrown01

The technology can totally be applied to the 951 - you just won't like the results. The system in the 951, unmodified, was designed to limit turbo-lag while spreading power across the rpm band and provide good top speed - they tried to find a "sweet spot" between a turbo big enough to provide the power boost they wanted while small enough to limit lag to reasonable levels.

You could get a newer, smaller turbo that would likely provide similar horspower and performance specs to the old stock turbo with very little or no lag, since the technology has come quite a way in the nearly 20 years since the cars were designed; that's just not the route most turbo-owners are looking to follow.

Emanuel

rage2

https://rennlist.com/forums/showthre...hreadid=104048

It's been done before, but it's not cheap .

I too believe that the reason for so much lag on our cars compared to others is because of the very odd plumbing involved.

turbite

1) Turn the engine around, that way the exhaust manifold is on the same side as the turbo.
2) Put the turbo on the same side as the exhaust manifold. (actually, this might be possible)

Sami951

Check the thread Rage2 posted above

This is also pretty cool -> http://www.lindseyracing.com/cust1a.htm

925T

It is possible to mount it om the rigth side.......

Lookat http://www.944968.com/

I think thats the way to go.......

// Niklas

turbite

I wish he showed a picture of how he plumbed the intake->turbo and turbo->IC pipes.

mumzer

i wish he would fix his freakin' oil leaks....my 11 month old has a cleaner undercarriage than that thing!