Georgia 84z28

Hi everyone. I am new to drag racing but not new to building. Looking for some advice on where i need to go from here to be as competitive as possible in my class, but still be able to drive on the street as this car is my daily driver. I have a 84 z28 with a mild build 355, comp 12-212-2 cam (.480 lift, 280 adv dur), flat top pistons, 062 vortec heads (stock with light port job), edelbrock performer intake, edelbrock 750 carb vacuum secondaries, electric water pump and fan, stock t5 trans, stock suspension (replaced all the bushings with polyurethane), shorty headers, 2.5" duals with h pipe and short glasspacks, stock rear gear (3.23), and 235 tires.
Im planning to replace the rear gear or the whole rear end but not sure if 3.50 or 3.73 would be the best option? Currently trying to find a set of iroc wheels so i can step up to a 255 tire, will this be enough or should i try and find some wider rears for the race tires? Looking at the summit stage 3 intake (airgap knockoff), any experience with it? Any other recommendations?
The series im trying to run requires mufflers, allows one power adder (turbo, nitro, blower), requires hard street tires and requires stock suspension in stock location.
This is my first time posting but i have been following this forum for a while so i know theres some awesome knowledge here. Any advice is very much appreciated! Thanks.

skinny z

When I first started racing my 86 IROC (RIP) I found the single biggest issue was traction. My combination wasn't too far removed from yours in terms of what the engine was. I ran a 700R4 rather than a T5 (which will be a point of discussion later).
When you say "hard street tire" does that exclude a DOT (street tire) racing "slick"? If it doesn't then get any one of drag radials that are currently out there. Mickey Thompson has revised their old favourite ET Street (a couple of years ago). That would be your first step. It the rule clearly means street tire, then get the widest, softest tire you can find and use them.
Then next issue with be lower control arm relocation brackets (LCARB). I doubt this would classify your chassis as being non-stock and it will give you the much needed tuning aid to help plant the tires. While on the topic of the rear suspension, besides the poly bushing upgrade you mentioned, it's long since been pointed out that the factory stamped steel parts don't do much for performance. The lower control arms and torque arm can be changed to any of the aftermarket replacements. Still stock configuration but with better parts.
You'll probably find that the 3.23 rear gear (and I hope it's a posi style) will be enough with the stick shift. My chassis likes the 3.73 rear gear combined with the low 1st gear of the 700R4 trans. That does present some problems though, mainly...traction. Without a slick, I'd be lost.
As mine is more of a street car than anything else, but has become faster over the years, I still haven't swapped out shocks and struts to a more drag race orientated variety. I've since installed air bags (Airlift Drag Bags) and they help a great deal. As your vehicle progresses and gets quicker, these are items you may also want to address also.
But as an entry level racer, get the first 60' dialed in with some consistency. DOT drag radials (if allowed by the rules) and LCARBs first.
Once you get enough starting line traction, you may want to consider replacing the T5 because by most accounts, it probably won't last.

AlkyIROC

Rules are in place to keep everyone in the class on the same playing field however there are ways around some rules if you know where to look.

As already asked, how strict is the "street tire" rule. MT ET street, although they have just enough rain groove to get a DOT classification, are really a slick in DOT form. With a more street tread, the MT Sportsman pro tires are very soft and there are many other tires very similar to these.

You won't get them in a very wide width but they'll fit nicely on a factory rim but you can buy some Blizzack winter tires. They're not cheap but they're also very soft plus they are a true street tire.

Best suggestion right now is to take the car to the track just as it is and see what it can do. No sense doing suspension modifications if it already has trouble getting down the track. You need some sort of baseline to start with to know which direction you need to go to make improvements.

Georgia 84z28

Unfortunately, the class rules specifically prohibit dot drag radials and even lists the MT as an example. Im looking at running some bfg t/a's for a road tire and a softer compound that i can change out at the track. Not looking to break the bank but what would you say is the best bang for the buck soft road tire?
I will have to ask the race official about the suspension upgrades and their definition of stock. I had been looking at all the parts you mentioned but pit it on hold due to the rules. I dont have the cash to dump in the car to be competitive at the next level since it is a heads up series.
Yeah, ive heard that the t5 starts coming apart around the 350hp mark but i figured id run it till it blew up and then swap in a t56. Ive found several rearends on craigslist, what works best in these cars? A 9" or a 12 bolt?
I really appreciate the fast replies and good info. Its nice to be able to bounce ideas off guys doing the same stuff or already done something similar.

rb85TA

A 9" has the appeal, it's about as strong as it gets, easy to change out gears (third member swap)... but there are disadvantages as well, it's heavier & takes more power to turn. Also because of the desire in the race & enthusiasts collective, they tend to be more costly.
The 12 bolt will handle 800-1000 hp if built right & is available from Strange as a direct fit replacement, takes less power to turn than the 9" and can be bought new for around a grand less than the 9".
But, if you are worried about the LCARB upgrade violating the rules. .. a rearend swap will definitely be a problem.
For your class & power level , you might consider a Dana 44, they were available as an over the counter upgrade from GMPP, but never installed from the factory & more than likely would be un-noticed at tech... vs a 9" or 12 bolt.

Night rider327

iTrader: (13)

Hey man. I think I met you today and sold you some parts. It was good meeting you.

With the class rules being true street tires, you will need to 'cheat' to put you on level playing ground as all the others that 'cheat'

You will want to soak your tires in a mixture. I used this for years in class racing long ago.
5 parts Xylene
1 part Acetone
Put it on with a paint brush about every hour for three hours.

If you must use stock suspension parts (non aftermarket), Then brace or box your LCAs. Weld in some flat stock to stiffen the LCA up. Also weld some flat stock to your torque arm in a triangle pattern to stiffen it up.

Get your timing curve set up right. A lot of people overlooks this. Change the weights and springs to get the curve moving right off idle and fully advanced by 2800-3000 rpm

articwhiteZ

iTrader: (56)

why do guys always worry it takes more power to run a 9"...lol.. 6hp loss any body can live with for the cost.
and as for heavier...get a good set of wheels..and the Wt is in a good place. 12lbs. use a alum 3rd member and it 8 lbs lighter then a 12bolt..lol
and you can swap gears in 45min..by yourself...just sayn.

Georgia 84z28

Wouldnt that make the tires fall apart very soon? I would think putting alcohols on there would make them prone to dry-rotting very quickly.
Yeah, ive got my advance curve very close but i definately need to work on the low end. Gotta get the spring set for my hei and tinker some.

Night rider327

iTrader: (13)

I wouldn't do it to a set of nice daily tires. It softens the tires up A LOT and makes then sticky/gummy. Works better than VHT on them. Yes they wear quicker (but so does true racing slicks) so just think of it as a set of racing tires that you swap on at the track and replace when needed.

When we use to class race, me and buddies would hit all of the used tire shops and buy all of the used tires in the size range we needed and keep those for our treated race tires. Only treat one set at a time and use those until they are dead., then move to next set, treat them and use them.

AlkyIROC

BFG T/A are not bad when they're new. Like every other soft street tire used for racing, the more you drive them on the street, the harder and drier they'll get.

Since the ET Street tires are not allowed, you can still run the MT Sportsman Pro tires. They're a really soft tire with lots of tread but like I just said, use them on the street very little if you still want good traction at the track.

https://www.mickeythompsontires.com/...m=SportsmanPro
The 26x10.5-15LT mounted on an 8" rim will work just fine. Even though they're made with drag tire compound, they still look like a normal street tire. Rule of thumb, air pressure in the tires should be around your ET so if you run around a 14 second 1/4 mile, you can air these down to 14 psi since they're still a wrinkle wall. The best thing about these tires is that they have a DOT rating and nowhere on the tire does it say "drag" so as far as anyone is concerned, they're just a performance street tire.

A radial tire like MT drag radials don't like low air pressure. 18-22 is about the lowest you want to go and many times 28-32 works best. Radial tires with low air pressure will cup up in the center of the tire and give you less traction.

As for a better rear end, no matter what you decide on, it will set you back $2k-$3k by the time it's in and ready to use. I use a 9" in my race car. As already mentioned, the minimal amount of power lost is not a big deal. I run an aluminum case, aluminum spool and aluminum pinion support. I can lift the center section in with one hand but I never need to change my gears. That's all unsprung weight. More weight saving than removing sprung weight.

Chances of finding the GMPP Dana 44 are slim and if it's in very good condition, the cost will probably be about the same as buying a 9" or 12 bolt.

skinny z

That's an excellent suggestion. I completely overlooked the Sportsman tire.

That's pretty close to the truth. My D44 was $750 USD. Then add LCARBs, a new gear set and master installation kit (all new bearings, shims and seals) and in my case a 2nd gear set and a couple of new bearings because the 1st set of bearings ate themselves up and there you have it. And I was still dealing with the original axles and housing. I could have had a completely new 12 bolt for the money I invested. Strength-wise, it could be argued that they're equal.

83 Crossfire TA

iTrader: (2)

the hot ticket for this kind of tire used to be the pep boys futura tires, I've run 1.7 60's on a set of them in 255/50-16. I've run similar times on factory goodyears in 245/50-16 (factory gatorbacks that came on an 87 formula 350 that the original owner stored in the attic for 18years) and 275/40-17 (goodyear GS-C's that came on my '97 TA). I've had similar luck on firestone wide ovals. I've never gotten TA's to go faster than low 1.8's on the 16" rims, but honestly if it meets the class I'd forget about the factory 16's and go with factory 15" rims ('87 factory TA/Formula 16's with tires weigh 54 and 56#, a set of '87 'bird 15x7's with 215/65-15's weigh around 36# and I've found 255 and 275/60-15's that are under 40# mounted on them and will give you way better traction. If you're allowed that tall a tire and you want to stick to 16's, then run some 295/50-16's.

Gear depends on powerband and actual power made. You will likely want to gear the car to cross the line at your shift point at the top of 4th gear (in this kind of thing I'd be tempted to gear for the top of 5th but in no way will 5th hold up to any real abuse in a T5). More gear means that it will be easier to modulate the throttle off the line and more gear also means less strain on the T5, I suspect that if you go with a 255 or 275/60-15 or 295/50-16 you might get away with 4.11 or even 4.56 gears.

Unless you find a radial tire that still maintains the contact patch integrity at low enough pressures for the sidewall to flex enough to absorb some of the shock of the launch, I'd skip the relo brackets, they'll just hit the tires too hard off the line too work right. The possible exception is if run the 275/60's, they might have enough sidewall to work.

If you're allowed to run a really tall tire I'd be tempted to look around for a 28-30" tall ice rated tire, maybe something like a 275/70-15...

huh, I could have some real fun with this. What class is this?