building for SCCA Solo BSP

[batchman]

Last year I campaigned for and received a rules change allowing update/backdate with all C4's together. This allows my (ok, my wife's) 91 ZR-1 with quick rack to be a legit entry in B Street Prepared. This year I'm getting back to sorting the car, with hopes of not getting killed by rally cars too terribly, at least on a regional basis LOL. So far so good with this site, good info here, thanks much.

But I think I need something like a wiki for low-impact power mods. *SP mods are reasonably open on induction (up to 1" into the head), exhaust, emissions and tune. So I find myself with some questions, and hit/miss success with search here. Perhaps with some help weeding through it all we can help carry the torch for Beasts everywhere.

Car currently has Watson headers, (I think) Random cats, Borla catback, a K&N drop-in, a DRM chip, and that's about all I can find for pre-existing power stuff. Dyno showed 335 at the wheels, looks like there's room for improvement.

1. Getting induction cool and dry. Seems straightforward to bypass the coolant in the throttle body, but doesn't appear feasible to dry out the injector housings. Is the upper plenum carrying coolant? If so, does it connect to the throttle body? Are phenolic plates the right answer from injector housing to plenum? Are they a common mod?

2. While I'm not wild about the idea, I think I'm going to be stuck port matching the heads without pulling them. I hope to go for plenum/IH/port match this winter. Any tips there would be helpful. Anything to be gained at the throttle body?

3. The car currently has a vacuum leak, and the vac pump appears to be bypassed. Since secondaries and brake booster seem fine, should I even worry about the pump? The vac schematic scares me some, mostly since it's clearly been messed with.

4. I'd like to remove the A/C and underdrive the WP/Alternator. I can't seem to find anything on the A/C delete, maybe it's fine for most but I'm worried about enough wrap on the power steering, which suffers a huge beating in autocross on big fat race rubber. Any resources/horror stories?

5. Any issues/benefits with removing emissions stuff? How/who to tune these cars? (sorry, my resources are all OBDII and Ford oriented) My state has stopped testing before OBDII, which is a good thing since this car is originally from Canada and emissions was always an issue, even with a stock PROM.

Sorry for having so many basic questions at once. Of course I'm also wrestling with suspension and brake issues at the same time. My hopes are higher than my budget at this point, but I'll feel a lot further ahead if I can formulate a plan.

For what it's worth, I'm also hoping to do a Fidanza, 3.54 gear, some sort of helical limited slip, and some sort of fix for the damned hubs and axle bearings.

Thanks for any comment!
- Jeff the hapless Ford guy...

[jonszr1]

335 seems a bit low for a car with your mods unless you are at 4k ft elev. you could contact corey henderson for the tuning andf injector housing and plenum porting. my car with fidanza jeal headers custom drgas exhaust porting by corey as well as tuning made 409.9 rwhp and 373.66 tq . you could contact either pete or randy woods of srp products about the air delelte. hope this helps and good luck this year

[Pete]

On the A/C you can remove everything with no issues.
You will need to run a shorter belt i think a 66 or 67 inch belt.

Pete

[batchman]

Thanks for the replies.

I had thought 335 may be a little soft, I am near sea level but in any case it's SAE corrected. 335rwhp looks like about 394 at the crank, the chip was worth about 10 (ran it both ways). I am not certain the cats are Random, but thought they were high flow.

The car has about 75k on it.

Any clues where HP falls off of these cars? I am figuring plug wires when the plenum comes off, do the coils degrade? They sure don't seem to be well located for cooling .

400 to the wheels sounds really good when considering some of the EVOs are hitting that. They don't scare me much, well there are a couple that do...

Thanks,
- Jeff

Originally Posted by batchman

Dyno showed 335 at the wheels, looks like there's room for improvement.

Almost every 91 I have seen has been down on power compared to 90's. My 90 made 339 stock.

1. Getting induction cool and dry. Seems straightforward to bypass the coolant in the throttle body, but doesn't appear feasible to dry out the injector housings. Is the upper plenum carrying coolant? If so, does it connect to the throttle body? Are phenolic plates the right answer from injector housing to plenum? Are they a common mod?

The upper plenum carries no coolant, other than the small passage from the injector housing to the pipes that are on the driver/passenger side of the plenum. Bypassing IMHO does no good, unless you cap it at the top of the injector housing and then the only benefit is when you pull the plenum in the future. The phenolic plates are another item that IMHO are money wasted. The motor itself is a big heat sink, and the heat radiates up. The only way to combat the heat is to make a injector housing/plenum combo out of injection molded plastic, or go to a sheetmetal intake design that allows more air to be pushed across.

2. While I'm not wild about the idea, I think I'm going to be stuck port matching the heads without pulling them. I hope to go for plenum/IH/port match this winter. Any tips there would be helpful. Anything to be gained at the throttle body?

Nothing to be gained at the TB until you start adding CI. Porting the top end will give you the most bang for the buck at this current point since you already have the headers. Port matching to the heads will make a difference as well.

3. The car currently has a vacuum leak, and the vac pump appears to be bypassed. Since secondaries and brake booster seem fine, should I even worry about the pump? The vac schematic scares me some, mostly since it's clearly been messed with.

The engine creates enough natural vacuum to run the car through the first few gears, top of third you should be running out of vacuum and 4th, is a waste. Since you are running autoX it can be left unplugged.

4. I'd like to remove the A/C and underdrive the WP/Alternator. I can't seem to find anything on the A/C delete, maybe it's fine for most but I'm worried about enough wrap on the power steering, which suffers a huge beating in autocross on big fat race rubber. Any resources/horror stories?

The power steering will have plenty of wrap, as the belt still has to come that way. Look at the diagram again, and as Pete said, I believe it is a 67" belt you are looking for.

5. Any issues/benefits with removing emissions stuff? How/who to tune these cars? (sorry, my resources are all OBDII and Ford oriented) My state has stopped testing before OBDII, which is a good thing since this car is originally from Canada and emissions was always an issue, even with a stock PROM.

You can remove the emissions stuff, what little there is. The air injection system can be unplugged and removed with no codes thrown by the ECM. Other than that, there is nothing left to really remove.

For what it's worth, I'm also hoping to do a Fidanza, 3.54 gear, some sort of helical limited slip, and some sort of fix for the damned hubs and axle bearings.

Fidanza will help in rev matching, but in the autoX group, you should be able to leave it in one gear and rev up and down with out changing again. of course this depends upon how your courses are set up.

3:54 gear set, find a set of stock gears.

The bearings, run the factory GM bearings, make sure you get some miles and heat cycles on them before you subject them to severe duty.

[batchman]

Since we bought this car it's had a soft brake pedal. Brakes are okay, will lock fronts on street, but it takes too much travel and too much effort.

Of course the first thing we did was flush the fluid. No sign of air.
Upgraded the pads, no change.
Switch to braided lines, no change.
Of course full flush each time.

Similar brake setup on our 88, and for that matter our 99 Cobra. Both those cars the brakes hit hard and are not an issue.

I gave up and changed the master cylinder, even though it held pedal steady once firmed up. Still a soft pedal, and maybe even longer travel. It's as if there is air in the ABS unit but I can find no specific method of bleeding same.

Have bled both by pedal and with a suction side power bleeder (venturi type). I've run at least 6 pints of fluid through this thing with all these successive attempts. Needless to say it's getting a little frustrating.

I'm going to try a pressure side power bleeder and open both wheels at the same time, hoping that with enough velocity we can sweep any trapped air out.

Other than the above we know nothing of the service history of the car other than it did in fact have a master cylinder and calipers. I wonder if there is any tech around for different master cylinder and caliper piston sizes found on C4s? Just because the MC we put in is fresh and labelled ZR-1 doesn't mean it's correctly sized. Similarly just because there are PBR calipers on this thing doesn't mean they're the right ones.

I think I will "trust nothing" until I can arrive at autocrossable brakes.

Thanks for listening,
- Jeff

[Pete]

Me and 3 others are using LS1 Camaro masters and never looked back.


Pete

[batchman]

Originally Posted by Pete

Me and 3 others are using LS1 Camaro masters and never looked back.

Now that's very interesting. Does this mean we're not the only ZR-1 with what I'd have to call "73 Buick power brakes"?

I'll have to noodle a bit on what you did to use the LS1 part. While the master is open in this class there can be arguments surrounding how it's done.

Do you know the piston size in the Camaro Master?

Thanks,
- Jeff

Originally Posted by Pete

Me and 3 others are using LS1 Camaro masters and never looked back.


Pete

Using the same in my ZR-1 with the Brembo 4 pistons front and rear.

[Pete]

Originally Posted by batchman

Now that's very interesting. Does this mean we're not the only ZR-1 with what I'd have to call "73 Buick power brakes"?

I'll have to noodle a bit on what you did to use the LS1 part. While the master is open in this class there can be arguments surrounding how it's done.

Do you know the piston size in the Camaro Master?

Thanks,
- Jeff

I know it has a bigger bore just never really measured it.

The early stock ZR-1 masters had some issues.

I made an aluminum spacer plate i think it was .150 or .200 thick to space out the master or you can cut the pin down so the master fits flush.

I will say the LS1 master has a much better petal feel.

Pete