Track Days in the DOHC Fiero

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Series8217
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Re: Track Days in the DOHC Fiero

Post by Series8217 »

Without ducting it's just a big heat sink. There isn't a significant amount of airflow in that location and the oil looks like a wall to slow-moving air. It will just go around it. At 200+ deg in the engine bay, a heat sink isn't very effective.
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Re: Track Days in the DOHC Fiero

Post by Shaun41178(2) »

Had to ask, sometimes the easiest things are overlooked
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Re: Track Days in the DOHC Fiero

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I thought i had mentioned earlier in the thread that I have to top off the oil after each session since about half a quart ends up going through the breather system. Looking back through my posts it seems I did not mention that here. Sorry!

Got a bunch of photos from Cali Photography. Here are my picks:

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Re: Track Days in the DOHC Fiero

Post by The Dark Side of Will »

Series8217 wrote: I hooked up my rear swaybar again in an attempt to limit body roll and get some more traction in the rear since I think it was limited by geometry and not weight transfer. Sure enough, the car is hardly looser but I've gained some front grip and the rear feels more planted too. However, the car now wig-wags on slide recovery (see: this part of my bloopers video). I know the 475# springs were already too much for the Koni reds, even at full stiff, but the rear swaybar makes it really obvious. I have a set of Bilstein struts waiting on the shelf for a revalve. I hope to get to those later this summer.
You still have the stock '88 top pivot locations, right? Have you looked at using camber plates or reworking the strut towers to move your top pivots inboard for more camber gain?
Series8217 wrote: I pulled the carpet out for my interior color change and didn't put it back in before going to the track. I didn't expect to have any problems related to that, but it turns out the carpet is pretty important. The Fiero has a ridge that runs down the center of the footwell in the exact spot where my heel rests. With the carpet removed, it's just that semi-gloss chassis coating on the floor. It's super slippery. I literally could not drive the car on the track in the first session. I got some gaffer's tape from my friend and put a few layers down. Problem solved.
The little things matter!
Ferrari uses a polished plate on top of the carpet on the side of the center tunnel so the driver's foot slides smoothly across it instead of having friction on the carpet.
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Series8217
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Re: Track Days in the DOHC Fiero

Post by Series8217 »

The Dark Side of Will wrote: You still have the stock '88 top pivot locations, right? Have you looked at using camber plates or reworking the strut towers to move your top pivots inboard for more camber gain?
Stock pivot locations.

For discussion of new upper strut mounts see: http://realfierotech.com/phpBB/viewtopi ... =3&t=17673
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Re: Track Days in the DOHC Fiero

Post by The Dark Side of Will »

I'm familiar with the upper mount discussion... I was just wondering about moving the pivot locations like FieroGuru did:

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http://www.fiero.com/forum/Forum2/HTML/000566.html#p7
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Re: Track Days in the DOHC Fiero

Post by fieroguru »

I don't have the file with me right now, but the camber gain with relocating the top of the struts is minimal with about .3 degree (I think) improvement over 6 degrees of roll and it really depends on the rear ride height and other mods (like my lateral link relocation kit).

Edit: checked the file and its .5 degree improvement over 6 degrees for a car lowered 1 1/2" and already running the lateral link relocation kit.
I autocross at the LS Fest and it doesn't have classes or modification rules (except it can't be a tube chassis or kit car).
Last edited by fieroguru on Wed Jul 16, 2014 6:46 pm, edited 1 time in total.
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Re: Track Days in the DOHC Fiero

Post by Series8217 »

Modification of strut towers is not permitted in NASA TT. Only simple slotting of mounting holes is permitted. I'm currently aiming for TTC after dyno reclass and mods, so I'm not going to modify the strut towers and have an illegal car.
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Re: Track Days in the DOHC Fiero

Post by The Dark Side of Will »

You already have a good aero setup, but I thought this one was pretty snazzy also:

http://forums.corner-carvers.com/showthread.php?t=48631

Looks like the whole front lip and splitter assembly just screws on when he gets to the track.
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Re: Track Days in the DOHC Fiero

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The Dark Side of Will wrote:You already have a good aero setup, but I thought this one was pretty snazzy also:

http://forums.corner-carvers.com/showthread.php?t=48631

Looks like the whole front lip and splitter assembly just screws on when he gets to the track.
Yep, Olsen's work is fantastic! I've always envied his garage as well.

My splitter comes off with 4 bolts, 4 nuts, and some plastic push rivets. It takes about 10 minutes to remove and replace. I just can't fit it anywhere else in the car, so it stays on during transit, and I keep the car high enough to stop it from tearing off on my driveway.

I'm shopping for a tow vehicle now so I can start doing things to the car that will make it more track capable but less street-worthy..... like a full roll cage, and maybe some lower aero bits.
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Re: Track Days in the DOHC Fiero

Post by Series8217 »

Pretty good weekend overall but the car seems to be losing my power. My fastest lap was the first hot lap of the entire weekend, despite not having driven the car for 6 months and having a bit of lap traffic. By the end of the weekend the poi's S2K was easily walking away on straights. :cry:

My fastest lap for each session was always one of the first two or three, with each subsequent lap dropping by a few seconds each.

I thought the issue might be due to tire pressures.. I'm currently running the Hankook RS3s at ~37 psi hot. Perhaps they like a lower pressure and my lap times are going up because the tire pressure is rising too high. I'm going to try lower tire pressures at the next event to see if that might be the problem. However, the sidewall flex I get from these tires is not too encouraging to lower pressures... refer to pic below.

I'll probably book a dyno test soon so I can see if my motor is doing OK (I think it's not).

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Re: Track Days in the DOHC Fiero

Post by Shaun41178(2) »

if you feel that you are dropping power when the engine gets hot after lap 1, then make sure you dyno your engine when hot. or do a cool pull, then several more back to back to back to see how much it drops off.

could you normally keep up with the s2k in the straights?
FieroPhrek working on that ls4 swap for 18 years and counting now. 18 years!!!!! LOL

530 whp is greater than 312
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Re: Track Days in the DOHC Fiero

Post by Series8217 »

Shaun41178(2) wrote:if you feel that you are dropping power when the engine gets hot after lap 1, then make sure you dyno your engine when hot. or do a cool pull, then several more back to back to back to see how much it drops off.

could you normally keep up with the s2k in the straights?
Yeah there's a dyno at the track so I'm going to see if I can dyno Saturday morning and then Saturday afternoon right after a session.

The S2k was always a little faster on the straights but now its a lot little faster.
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Re: Track Days in the DOHC Fiero

Post by The Dark Side of Will »

Interesting. Your coolant and oil temps are under control, but the car gets slower--strongly suspecting loss of power--throughout the session.

That sounds like heat soak on a supercharged engine, but that's not what's going on here... can't get 250 degree intake temps in a 220 degree engine.

Does your ECM do knock retard? Is the knock sensitivity a function of coolant temp? Something in your ignition system getting weak with heat?
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Re: Track Days in the DOHC Fiero

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The Dark Side of Will wrote:Interesting. Your coolant and oil temps are under control, but the car gets slower--strongly suspecting loss of power--throughout the session.

That sounds like heat soak on a supercharged engine, but that's not what's going on here... can't get 250 degree intake temps in a 220 degree engine.

Does your ECM do knock retard? Is the knock sensitivity a function of coolant temp? Something in your ignition system getting weak with heat?
When I first noticed the problem I swapped the entire ignition system out. No noticeable change in behavior.

I'm thinking knock retard or I melted another cat. The induction sound from the engine did seem to be getting louder.
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Re: Track Days in the DOHC Fiero

Post by The Dark Side of Will »

Different subject...

When I'm popping a U-turn in my Formula and gun the throttle mid turn, it unloads the front and plows like a tractor. The Mule does the same thing. It's a little frustrating that I have over 300 RWHP in a 2900# car and I can't kick the back end out making a u-turn.

Does your car do this? I was wondering if my cars do it due to inadequate anti-squat. Your car should have more than stock anti-squat, as FieroGuru's outer pivot relocation brackets lower the trailing arm pivot, which increases anti-squat.
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Re: Track Days in the DOHC Fiero

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The Dark Side of Will wrote:Different subject...

When I'm popping a U-turn in my Formula and gun the throttle mid turn, it unloads the front and plows like a tractor. The Mule does the same thing. It's a little frustrating that I have over 300 RWHP in a 2900# car and I can't kick the back end out making a u-turn.

Does your car do this? I was wondering if my cars do it due to inadequate anti-squat. Your car should have more than stock anti-squat, as FieroGuru's outer pivot relocation brackets lower the trailing arm pivot, which increases anti-squat.
I can't remember if my car still does that but a long time ago it did -- before I did any suspension tuning at all. I generally don't try to spin it out on the street and there aren't any tight enough corners on the track that I have enough torque at the wheels to step the rear end out on corner exit.

What's your static rear toe, and how much dynamic toe-in do you get when you jump on the throttle?

It may just be the nature of the beast... huge rear weight bias (58% for a stock Formula.. that's 1700 lbs over the rear axle, or the equivalent of a 50/50 car that weighs 3400 lbs). Even if you are breaking the rear tires loose you've got a big forward thrust to plow the car toward the outside of the turn.
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Re: Track Days in the DOHC Fiero

Post by The Dark Side of Will »

Series8217 wrote: It may just be the nature of the beast... huge rear weight bias (58% for a stock Formula.. that's 1700 lbs over the rear axle, or the equivalent of a 50/50 car that weighs 3400 lbs). Even if you are breaking the rear tires loose you've got a big forward thrust to plow the car toward the outside of the turn.
I was hoping to get a data point out of you to figure out if increasing the anti-squat helped or not. I may just have to put in a steering quickener and hit the u-turns faster. The car's low moment of inertia means that even after the chassis is "committed" to the turn, hammering the throttle still eliminates that angular momentum instantly.
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Re: Track Days in the DOHC Fiero

Post by The Dark Side of Will »

Series8217 wrote: It may just be the nature of the beast... huge rear weight bias (58% for a stock Formula.. that's 1700 lbs over the rear axle, or the equivalent of a 50/50 car that weighs 3400 lbs). Even if you are breaking the rear tires loose you've got a big forward thrust to plow the car toward the outside of the turn.
I was hoping to get a data point out of you to figure out if increasing the anti-squat helped or not. I may just have to put in a steering quickener and hit the u-turns faster. The car's low moment of inertia means that even after the chassis is "committed" to the turn, hammering the throttle still eliminates that angular momentum instantly.

Static rear toe is stock. I know my dynamic shouldn't be any different... ;) It isn't on the Formula and won't be on The Mule once I get the spherical bearing control arm pivots installed.
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Re: Track Days in the DOHC Fiero

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The Dark Side of Will wrote: Static rear toe is stock. I know my dynamic shouldn't be any different... ;) It isn't on the Formula and won't be on The Mule once I get the spherical bearing control arm pivots installed.
Even with sphericals you still have bump steer, so your dynamic toe is not the same as static.
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