fieroguru at lsfest

Fiero topics such as vendor reviews experiences, car shows, Fiero buys acquisitions, Fiero Photography.

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Shaun41178(2)
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fieroguru at lsfest

Post by Shaun41178(2) »

How did you do? I haven't seen a thread on Old Europe about it. If I missed it feel free to post it here
FieroPhrek working on that ls4 swap for 18 years and counting now. 18 years!!!!! LOL

530 whp is greater than 312
AkursedX
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Re: fieroguru at lsfest

Post by AkursedX »

It's in his build-thread.

http://www.fiero.com/forum/Forum3/HTML/000123-23.html
The trip down the car averaged 29mpg again... breaking the 30 mpg mark is looking to be difficult.

On the first day of LS Fest, I was able to do ten 1/4 mile runs and six passes on the autocross track. Overriding theme is the car has too much power/not enough traction.

On the drag strip, I started out going though the water box, quickly nixed that idea as I would launch quicker w/o any pre-launch burn out. I also started out launching the car right off idle in 1st gear... Doing this I would still spin at the top end of 1st, which was hurting my ET and MPH. So I started launching in 2nd gear... slower out of the hole, but resulted in my quickest ET and mph of the day. Even launching in 2nd gear, wheel spin still happens as I feed it more throttle... need better and wider tires.

The major issue with 1/4 mile performance is the 2-3 shift... its like the syncro locks me out of the gear and I have to hold/apply pressure to it for well over 1/2 second for it to slide into gear and commence with the run. I am shifting at the same RPM (about 7k) but the 1-2 and 3-4 shifts both happen relatively quick. I adjusted the throttle follower torque to pull more torque so it would close faster early on with the tune. So its possible the engine is now dropping RPM too fast and passes up the RPM of the 2-3 gear shift before I get the shifter pushed up and over. The 1-2 shift has a larger RPM drop and the shifter is pulled straight back so there is more time to grab second and its a quick shift being pull straight back. The 3-4 shift is also quick... so I think I can just pull the shifter back quicker than forward and to the next gate over. So tonight I will tweak the throttle follower in the 4500-7K range to see if it helps the 2-3 shift by dropping RPM less quickly.

Best time of the day was 12.896 @ 114.10 mph... I know the car has more in it if I can get it to hook and speed up the 2-3 shift.

The 6 runs on the autocross were all steps towards a better time. 1st run I DNF'd as I missed the first cross over turn and the announcer came over the intercom "your going the wrong way"... 2nd run was 57.089 where I spun out on the back stretch, then 44.908, 44.784, 42.699, and 42.294. The best time of the day was in the 36 second range, so my times suck! I run the course in 2nd once I take off in 1st, but traction in 2nd gear is easily overcome in the straight line, let alone going around a corner, so less throttle lets the car go faster.

The car really needs a driver mod, wider stickier tires especially in the rear, and fix the 2-3 shift issue... but its been fun flogging the car!
'88 Fiero GT- 3800 Turbo Best E.T. 11.36 Best MPH 121.50 (Sold and gone)
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Re: fieroguru at lsfest

Post by Shaun41178(2) »

Cool. Thanks
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Re: fieroguru at lsfest

Post by Shaun41178(2) »

Just noticed jgunset had his ls3 Fiero there and ran a best of 13.05
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Aaron
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Re: fieroguru at lsfest

Post by Aaron »

Before I go into the questioning, mad props for the quality build and actually racing the car.

Now the question I have. He mentions over and over his traction problems. Who here has traction problems in their swapped Fieros? I'm on stock wheels/tires/suspension/Getrag, and if I hammer it from idle, it will hold traction in every gear. If I try I can spin the tires in 1st without a problem, but it takes concentrated willful effort. The car won't do it on power alone, and certainly won't in 2nd.

I'm wondering why this is? I have little doubt I'm making more power than he is, although he has me beat in torque of course. I guess that could be it, but I'd think my car would go crazy when the turbo comes on and I gain 200whp and 200wtq in 1,000rpm. Instead my car just squats hard, plows the front end, but hooks the rear.

It just seems weird how many people mention traction problems, and I haven't run into any. And it isn't because I'm not making the power, I put car lengths on my Jeep which runs 12s. I hate to jack this thread, just seriously confused.
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Series8217
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Re: fieroguru at lsfest

Post by Series8217 »

Aaron wrote:Before I go into the questioning, mad props for the quality build and actually racing the car.

Now the question I have. He mentions over and over his traction problems. Who here has traction problems in their swapped Fieros? I'm on stock wheels/tires/suspension/Getrag, and if I hammer it from idle, it will hold traction in every gear. If I try I can spin the tires in 1st without a problem, but it takes concentrated willful effort. The car won't do it on power alone, and certainly won't in 2nd.

I'm wondering why this is? I have little doubt I'm making more power than he is, although he has me beat in torque of course. I guess that could be it, but I'd think my car would go crazy when the turbo comes on and I gain 200whp and 200wtq in 1,000rpm. Instead my car just squats hard, plows the front end, but hooks the rear.

It just seems weird how many people mention traction problems, and I haven't run into any. And it isn't because I'm not making the power, I put car lengths on my Jeep which runs 12s. I hate to jack this thread, just seriously confused.
Gearing being the same, torque is what matters here.

Tires are obviously extremely important.

Launching the car is in no way the same as flooring it from idle.

Also, once you start turning (road course/autox) the game changes, because the rear tires have two duties. Its easy to break the rear tires loose if you're cornering hard enough, even with low torque at the wheels.

flooring it from idle with 220 ft-lbs to the wheels multiplied by 1st gear I don't have any issues.... But I also have fresh 275 hankook rs3s. When I had heat-cycled 255 Pirellis I could get wheel hop shifting into second at the strip, and first gear was nearly useless without a perfect launch.
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Re: fieroguru at lsfest

Post by fieroguru »

Shaun41178(2) wrote:How did you do? I haven't seen a thread on Old Europe about it. If I missed it feel free to post it here
Yes, everything is in my build thread in the construction zone.
Shaun41178(2) wrote:Just noticed jgunset had his ls3 Fiero there and ran a best of 13.05
Yeah, he was cool to hang out with. Our cars are within about 10-15 whp of each other (his is higher), but the power bands are quite different. He was having major traction issues (stock fiero 14" wheels and stock sized tires) with 2nd gear launches, so I suggested he use less launch RPM to get out of the hole and let the torque of his engine do the work. He probably has 100ft-lbs more off idle than I do. This resulted in his best trap speed of 116mph. We were able to run head to head on one race... I just wish someone would have video'd it as you don't see 2 fieros heads up that often.
Aaron wrote: Now the question I have. He mentions over and over his traction problems. Who here has traction problems in their swapped Fieros? I'm on stock wheels/tires/suspension/Getrag, and if I hammer it from idle, it will hold traction in every gear. If I try I can spin the tires in 1st without a problem, but it takes concentrated willful effort. The car won't do it on power alone, and certainly won't in 2nd.

I'm wondering why this is? I have little doubt I'm making more power than he is, although he has me beat in torque of course. I guess that could be it, but I'd think my car would go crazy when the turbo comes on and I gain 200whp and 200wtq in 1,000rpm. Instead my car just squats hard, plows the front end, but hooks the rear.

It just seems weird how many people mention traction problems, and I haven't run into any. And it isn't because I'm not making the power, I put car lengths on my Jeep which runs 12s. I hate to jack this thread, just seriously confused.
I was having traction issues at both ends of the car, rear wheel spin and locking up the fronts on the autocross. The front is largely due to the 205 all season front tire and needing to do some work to adjust in more rear bias (never locked up the rear).

Traction issues at the rear was only under acceleration. Understand, my car has around 280wtq at 2000 rpm, 300wqt from 3400-6600 rpm, and it comes on instantly when I mash the throttle.
Image

It also is near stock weight (2807lbs with 1590lbs on the rear). Compared to Stevens car I have 5 lbs less weight on the rear, but about 30 lbs more in the front. I put some new 245/50/16 BFG G-Force Sport Comp 2 tires on the rear a week before LS Fest, but don't care for them at all. They have slightly better forward traction than the old 245/45/16 kumho's but the sidewalls have too much flex for my taste. First gear*FD in the F40 is much higher than the 282 getrag, so instant torque + near stock rear weight + less than ideal tires = instant wheel spin. 2nd is slightly better with the new tires, but launching at the strip in 2nd I had a hard time finding the right RPM/clutch technique to launch at to avoid wheel spin and bogging the engine (12 lb aluminum flywheel).

The car really needs better wheels/tires front/rear, just isn't going to happen this year. I would like to put some 17" 225 or wider tires up front and some 18" 295's in the rear with a really good compound tire, but besides the expense of the wheels/tires, I have to get shorter axles as well, so that isn't happening until after my garage is built in 2014.

I haven't done much work to the car since the LS Fest, just driving it daily.
I did do some logging of 2-3 shifts north of 6500 rpm and it was taking anywhere from .8 to 1.5 seconds to accomplish... Since then I have reverted back to the stock throttle follower settings, rebuilt the sloppy shifter and even used some aluminum can material to further reduce pivot clearances, repositioned the shifter base to make it harder to accidentally hit the 3/5 transition (shifter was slightly rotated so 1/3/5 were about 1/8" closer to the driver than 2/4/6). The next step is to disassemble the shifter mechanism at the transmission and beef up the spring load that self-centers to the 3/4 gate. With the longer cables and my routing, there might be enough drag that the transmission doesn't self-center fast enough to 3rd gear.
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