The thread about the best tires for street traction got me thinking, what is the approx HP limit without resorting to spinfest? While 800 hp sounds great spinning at 60 into a ditch doesn't sound so great. I would like to keep the power manageable with a 305 rear tire and an auto equipped with 3.73 gears. I understand it has a lot to do with throttle modulation but from experience, I know there are a LOT of high HP cars here, what are some opinions on max HP based on a good performance street radial.

 

There's so many variables to this. You mentioned 305 but what size rim? 18?

Are we talking from a dig? Roll racing? 60-130?

I was around 430rwhp with a 3.90 rear and 305 30 19 R88Rs. I could nail it in 2nd at 40mph and it would dead hook.

Added a supercharger and was around 600rwhp. Same tire. It would occasionally break loose from 60mph in 3rd gear.

Also depends a lot on surface and temps.

 

Mine breaks loose in second gear with only 340 wheel horse, 3.73 gear and 3200 stall in 30-40 degree weather with Bridgestone pole position tires, 305, 30, 19. Yes, surface temps have a lot to do with traction. I agree with EshoreMD, lots of factors, different builds, different cams giving different torque numbers at different RPMs. With these A4 transmissions, you really need a drag radial or slick to launch it depending on your build. I use a set of street tires for daily driving and I bought a set of rear rims with a drag radial on it for when I want to go play. I haven’t tried them yet, hopefully this spring.

All summer only tires perform about the same unless your running a 200TW tire which should give you better traction,

I’ll say 400-450 wheel horsepower is fine for a summer only tire. Expect spinfest if trying to launch in first gear. 90 degree weather would help, but im near Chicago, only happens in June, July, or August. Put a magnacharger on it and expect spinfest through 1st and second gear with all the low end torque they produce.

 

Currently 305/30-19 Nitto 555G2's. I do understand where and when the torque hits has a major effect on traction. I plan on a mix of dig and roll racing, drag and drive events most likely running the 11.00 class and using drag radials on the track. The engine build part of this is still up in the air, I am starting at the back with the diff and transmission, rebuilding the torque tube then the engine. Mine has 130,000 on it, I won't lean on the engine without a rebuild/refresh or total replacement. What is for sure are 3.73 gears and a worthy transmission, most likely an RPM with a converter in the 2800 area. I'd like to see 600 wheel, with a 6500 rpm redline, how I go about that I am still learning. Reading the builds and threads here has been an unbelievable resource, it really helps narrow down what direction I want to go, so thanks!

 

I'm probably going to try the Mickey Thompson ET Street S/S in 305 35 19 this spring.

 

600 wheel, 3.73 gears, and converter. You’re going to spin fest any street tire. Better off with a 200TW tire, for example, falken 660 or Bridgestone 71RS. You’re going to need an all season if driving under freezing temps.

Sounds like a fun build, be careful out there.

 

It is often about the use of the right foot.

Learn to use the throttle wisely.

on the street you generally never use more than 400 Hp and if you do you risk arrest or crashing. That is what we see on the web.
This is just one of several reasons the Cirvette team says the C6 GS is the best track car. Less power often makes easier and faster lap times in stock configuration. Plus you have the better brakes and coolers.

 

Is this a theoretical post, or what?
The traction control and active handling on these cars works pretty well.
I have 500HP, and I can break the 325 Indy Firehawk tires loose at anytime in gears 1-3. That's why I only turn off TC/AH when I'm in a BIG parking lot with nothing to hit.

 

Buy an Eray if you want traction.

 

even my lowly leaf will easily spin the tires if I mash the pedal when stopped. And up to about 40 mph if there is a drop of water anywhere. and that's only like 200 hp lol. FWD but the issue is the same.

Point being I'm not sure what you're asking here. My stock auto with the 2.73 is already fighting for grip off the line, it's a delicate balance between transferring the weight to the rear tire and not having it spin. The "new" shocks help a lot but I still can't mash it or it will spin. The only way I can "mash the gas and go" is if it's dry, warm, and in a perfectly straight line..

You would be a lot better off correlating the weight transfer with pedal position and learning how to squeeze on the pedal to the point where the tire is "slightly slipping but not spinning", and how to control the car in low traction. Instead of just fitting the "stickiest" tire you can find, stabbing wildly at the pedal, and hoping for the best.

Now if only I could explain that to the typical detroit uber driver

 

Or to put another way, once the pedal can hit the floor without breaking traction the car needs more power 😇😏

 

🤨 Drag racing monkey business 🙄

 

No. I would not waste my time or others here with bullshit questions. Trac control and AH work OK until they don't, being a 2000 with a fried non repairable EBCM mine don't. Which is fine with me, I don't need nor want 25 yr old nanny computers "helping" me.
I'll build for 600 wheel and go from there. Thanks to those who offered their advice.

 

It was already mentioned, it is all about throttle modulation.
If you can't manage that, then park the car.

 

I manage just fine but thanks for the advice.

 

My car is a weenie 366hp and if I roll into it and then floor it, the tires smoke about 3500 rpm until I lift or up shift. Thing is, I’m on 35mph streets and I don’t want a ticket or lose control, so we’re talking short rips. Maybe a more remote road I’ll run through second up to about 85 and let off.

With 600 wheel I think you could smoke any street tire at will, which you could probably do with 450 hp (520-ish crank hp). So definitely a drag radial for fun days. Even then, streets are rough and traction is always going to be sketchy. Maybe spend more on good suspension upgrades that assist with traction and a little less on hp. I think the end result is quicker and more controlled acceleration. I like you’re thinking on starting the project from the differential and working your way forward. But any racer will tell you the magic is in the suspension.

Oh…and be sure to modulate, lol.

 

I will build the engine last. I agree, currently going through the suspension. Delrin bushings, new BJ's, tie rods, links. I am a former suspension designer, the dialing in process with geometry is something I enjoy. Then gears and transmission, freshen up the torque tube and shaft. Brakes are next, then the engine. I am an older guy, my street and competitive racing days are WAY behind me. I do plan on drag drive events and spending some time at the road course near me. I have raced bicycles, motocross as a semi pro privateer, piloted a 9 sec Harley, autocrossed a 315 fwhp Saab 900 (an advanced course on throttle modulation) and so on. I even pulled off a rarity, piloting a gen 1 Viper (no ABS, no AH, no TC, **** ton of torque) in fury around the Chrysler proving grounds course without putting it into the weeds, something several engineers and test drivers cannot say. Even RC cars, raced them quite seriously years ago. In other words I have the chops to know when to hit it and when not to. And I 100% agree, suspension is everything in getting power to the ground safely and effectively. This holds true in every form of motorsport, even sport without a motor, like bicycles. Trust me, going 40 mph down a mountainside on a bicycle requires some pretty spot on suspension settings.

 

Are you ballparking a goal of 600 at the wheel?

My last one was 500 wheel which is VERY easy to drive and maintain traction with a decent 200tw street tire in 305/30r19. This was also a centrifugal blower so power rolled on in a linear fashion and was RPM related.

I drove a 625rw LS6 with jam cam and centri blower and that felt like about the happy sweet spot for me on the street. I don't know that I would want more. I wish I remembered his tire combo, but it was on square C5 Z06 18" wheels. I was surprised how good the traction was. It was not a hand full to drive. It was actually very docile and sounded crazier than it was. I believe it was sticky street tires. R888 maybe? But it gripped and I was surprised for the power. I did not throw that one through corners, didn't have the opportunity, nor would I send someone else's car with that much power, so I can only comment on straight line.

 

Yes, roughly targeting 600 wheel though I still have no idea how I will attain that goal. My motor is pushing 130,000 and will require a rehash or replacement. Being a 70's kid the feeling of push you in the seat torque is intoxicating, I'd like to go that route though the high end rush of FI is also good stuff. But that is after everything bolted up to the engine back is freshened up first. Fell for the "build the engine and a month later replace the trans" trick too many times before. Not to mention my getting old beat to **** body puts up a major bitch at that kind of activity.

 

I've done NA big h/c with rpm and I've done stock h/c with a blower. Stroker/twins is a fully new concept for me and probably mismatched since I switched it up mid-project.

That said.... a generally Stage 1 mild cam with some factory heads CNC ported (or even just a stock cam) and adding 8 to 10psi of centrifugal boost is a very sweet combo. I have been EAGER to leap out of some cars in the past after 90 minutes of driving. Gas fumes permeating your clothing and hair. Feet and legs sweating through and skin burned. Shaken in a blender at every stoplight. Absolutely fun to partly deafen myself with that combo.... but when I had the SC combo I decided "this is living." You can still enjoy a factory C5 miles per gallon and cruise comfort with none of the detractors but then put your foot in it and take off like a shot. Best of all worlds. And should you want less power... or more power... you just change the pulley diameter. If you want that wall of power to come on earlier, a smaller pulley has it spool sooner and you can run a bov basically as a wastegate so it hits 8psi at 4k rpm instead of 6500 and holds it through the run (depending on impeller rpm limits). Lots of combos and options there. It's like cheat mode.