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-   -   Whats the right amount of horsepower? (https://www.rx7club.com/v-8-powered-rx-7s-299/whats-right-amount-horsepower-1089767/)

BLUE TII 10-15-15 09:06 PM


ZDan

Treadwear numbers are not directly correlated with grip. Particularly grip on the street. At 50F in normal street driving conditions, good high treadwear all-seasons can have significantly more grip than Max or Extreme perf summer tires.

Best tires for grip depends on usage conditions. And even for dry track usage you shouldn't assume lower-treadwear # => more grip. There are tires that have poor grip and wear out quickly.


In normal steet driving conditions you don't need grip... Yes, if you need to emergency stop when your tires are cold the distance will be longer, but in my normal driving there is someone behind me in an SUV that keeps me from ever using maximum braking.

If... you were alone... at night... 1 mile from your house...and a person jumped out in front of you... you might stop shorter and not hit them on all-seasons.

You probably just should have steered around them instead of hitting the brakes.

Push the Max performance street tires or DOT Rs a bit and they warm up and have much more grip.

You should say the high treadwear all-seasons are "more predictable" since they always have the same mediocre level of grip.

But 50 deg F?
No, its more like 35-40 deg F pavement temps (you usually notice it in the mornings) that max performance summer or DOT R tires won't heat up in normal sedate driving.

There are a couple tires that are terrible before they are warmed up even in temps as high as 50 deg F as you say. You can usually tell those because people in really hot climates love to race on them.

Our whole winter season of auto-x is 45-55 deg F and the only thing faster than max performance summer tires is full race tires. Even if it rains torrents no one wants all-seasons. Its full tread performance tires or REALLY SOFT rain race tires (that last minutes if it dries out).

I maintain my viewpoint that all-seasons in wide performance sizes are for basic people who bought a performance car/package for image and then were too cheap to pay for the actual performance.

BLUE TII 10-15-15 09:07 PM

And I think this is the PERFECT thread to be having this tire conversation...

ZDan 10-16-15 07:00 AM


Originally Posted by BLUE TII (Post 11980339)
In normal steet driving conditions you don't need grip...

You *MIGHT* need it suddenly and unexpectedly.


Yes, if you need to emergency stop when your tires are cold the distance will be longer, but in my normal driving there is someone behind me in an SUV that keeps me from ever using maximum braking.
100% of the time? You want maximum grip for real-world conditions on the street for that fraction of a fraction of a percent when you really do need it!


If... you were alone... at night... 1 mile from your house...and a person jumped out in front of you... you might stop shorter and not hit them on all-seasons.
This brings up a broader point I'd like to make: you cannot broadly categorize tires in terms of grip based on whether they are summer tires or all-seasons. There are all-season tires that are pretty well trackworthy (for a few laps anyway), there are some that have fantastic grip in warmer weather but suck in colder weather, and there are all-seasons that suck in all conditions.

Likewise there are wide variations in summer tire performance.


Push the Max performance street tires or DOT Rs a bit and they warm up and have much more grip.
Problem is, in the real world on the street, they're going to spend 99.9% of their time much cooler than their optimal temps. Even more true if they are wide tires on a relatively light car. My FD on 245/275 Michelin Pilot Super Sports has less grip on the street at 50F than our Mazda3 on General GMAx AS-03s. But of course the PSSs have WAY more grip at the track.


You should say the high treadwear all-seasons are "more predictable" since they always have the same mediocre level of grip.
AGain, you can't broadly say this about all-seasons. There are some that have barely less grip than Max Performance tires on the street (Michelin PS A/S 3). There are some that are skewed more to colder weather and snow. There are some that have reasonably stiff responsive sidewalls and plenty that don't. And there are some that just flat suck in all conditions (Bridgestone RE92, which probably prevented us from buying a new Mazda3 a couple of years back).


But 50 deg F?
No, its more like 35-40 deg F pavement temps (you usually notice it in the mornings) that max performance summer or DOT R tires won't heat up in normal sedate driving.
I've noticed it with the PSSs even after 15 minutes at 70-75mph. Very surprised at the very low cool-weather grip of those tires, IMO their not as good as the RS3-V2s on my S2000. Again, exacerbated by being sorta wide tires on a sorta (relative to modern pigs) light car vs. narrower 205/225 tires on the S2k.


Our whole winter season of auto-x is 45-55 deg F and the only thing faster than max performance summer tires is full race tires. Even if it rains torrents no one wants all-seasons. Its full tread performance tires or REALLY SOFT rain race tires (that last minutes if it dries out).
I would never suggest any all-seasons for autoX, even in the wet, that wasn't my point.


I maintain my viewpoint that all-seasons in wide performance sizes are for basic people who bought a performance car/package for image and then were too cheap to pay for the actual performance.
Can't broadly categorize either tires or the people who buy them!
If I'm getting tires for real-world street driving (i.e., not autoX, not racing, not canyon-carving) throughout the colder months (not snow/ice mind you, but say 35-50F and sometimes wet), I would definitely pick a top UHP all-season over any Max Perf summer tire.

Also reject the idea that cheap tires inherently have poor grip and that expensive tires are "better". There are GREAT tires available for reasonable bucks, and plenty of expensive tires that suck!

You just can't make any broad characterizations on tires.
Too many people think they can just buy by the brand and be OK, but no, most major brands make good tires and suck tires in all categories.
Likewise, you can't assume that a specific Max Performance summer has more grip (even in dry warm conditions) than a specific UHP All-Season, or that lower treadwear rating = more grip.
Nor can you assume that an "all-season" tire will have good grip in cool or cool/wet conditions, there are plenty that don't!

It's not enough to go by treadwear numbers and summer vs. all-season. Have to research the performance of the specific tire make/model to ensure your getting the best for your usage conditions.

wa11yba11s 10-16-15 10:01 AM

I think the HP number not only depends on the tire size, but also the gear ratio of your rear. If you have one of those lower geared diffs you might not be able to use 500HP.

gnx7 10-16-15 03:53 PM

I think 1000rwhp+ is a bit much on the street :)

In all honesty more than 550rwhp is hard to put down on the street unless you have an R-compound tire out back with 100 tread wear or less. A 275/35/18 can put down 595rwhp (440ci LSx) with 3.55's no problem.... if you want to overwhelm the tires you certainly can.

A 335 R compound out back really allows you to use HP. It's stupid to try to run a ton of HP with tires that aren't the best.

Littleguy 10-16-15 05:51 PM


Originally Posted by ZDan (Post 11980309)
There are tires that have poor grip and wear out quickly.

Good point! lol.

Nick Ritter 01-04-16 01:44 AM

288whp through t56 bone stock 6.0l through 4.10 gears very fun street car kinda quick compared to what you see on the street 2700lbs

BLUE TII 01-04-16 02:41 AM


gnx7

I think 1000rwhp+ is a bit much on the street


Where else can you use that much power but the freeway?

Its not really even going to help on the 1/4 mile- chassis set-up will get your times lower easier.

Freeskier7791 01-05-16 10:34 AM

what do you guys think about V8 swapped FB? 400whp?

XLR8 02-23-16 03:02 AM

I think it comes down to the purpose of the car. For me, I wanted 500-550whp as I felt that it was the limit of what was useable on the street. It's fun, and keeps me smiling all day. I break my 285's loose with half throttle in 4th if I give it the beans. But for a 30 series, they hold quite well with the Fordtrac 3.55's out back.

LargeOrangeFont 02-23-16 08:06 PM


Originally Posted by XLR8 (Post 12030841)
I think it comes down to the purpose of the car. For me, I wanted 500-550whp as I felt that it was the limit of what was useable on the street. It's fun, and keeps me smiling all day. I break my 285's loose with half throttle in 4th if I give it the beans. But for a 30 series, they hold quite well with the Fordtrac 3.55's out back.

What tires are you running?

Mr3plus1 02-23-16 08:15 PM

Depends on suspension/tire combo. I agree with most everyone saying 400-450. When I had mine I was running 335's in the back and they were r888s. While it definitely could have handled a lot more than the 400hp I threw at them I was still faster than 99% of the cars that I came across just driving around.

LargeOrangeFont 02-23-16 08:48 PM


Originally Posted by Mr3plus1 (Post 12031216)
Depends on suspension/tire combo. I agree with most everyone saying 400-450. When I had mine I was running 335's in the back and they were r888s. While it definitely could have handled a lot more than the 400hp I threw at them I was still faster than 99% of the cars that I came across just driving around.

R888s, NT01s, RC-1s or drag radials are almost a necessity with these cars over 400 WHP

The problem is getting and keeping heat in the 100 treadwear tires so they can really work well.

Ruler_Mark 02-25-16 03:25 PM

All the horsepowers

BLUE TII 02-25-16 05:24 PM


Ruler_Mark

All the horsepowers


Exactly!

Because there is always going to be someone faster than you, but maybe with enough HP you can beat them?

LargeOrangeFont 02-25-16 05:48 PM


Originally Posted by BLUE TII (Post 12032046)


Because there is always going to be someone faster than you, but maybe with enough tire you can beat them?

Fixed.

Littleguy 02-25-16 05:52 PM

Hahahaha

BLUE TII 02-25-16 06:56 PM

You just start from a higher roll on speed.

"Nah man, I spin anything under 160mph- lets roll on from 165mph."

From and actual imaginary conversation I just had.

Sai-Omega 02-25-16 08:19 PM

Reading through this makes me glad that my motor is putting out 527 at the crank.

The car ought to be a blast when I get finished.

ZoomZoom 02-26-16 11:40 AM

My LS3 FD put down 440/440 at the wheels and only drag radials could put the power down. One thing you need to consider is your rear end gear. The LS swap is already going to have a ton of torque off idle unlike you ever experienced with the rotary. This will equate to traction issues given the rear end and rear end gear you will be running.
If you are sticking with a stock FD rear you will likely be running a 4.10 or a 3.90 from an Automatic FD.
If that is the case expect plenty of wheel spin in 1&2 gears. If you are moving to a Ford 8.8 and a 3:55 gear it's going to be easier to put 400/400 down.

XLR8 02-26-16 07:53 PM


Originally Posted by LargeOrangeFont (Post 12031212)
What tires are you running?

Hankook EVO12's. They are pretty old, as I have put about 3k miles on my car in the last 5 years...lol. I got them as a quick solution. They definitely don't do bad though. On warm days, they hold pretty well. I definitely see a drag radial in my future though. A 15x10 Meister would look nitto too. ;)

runyun 03-17-16 09:21 AM

472 whp / 455 tq here.. I think its a bit much.
(was 345 rwhp previously - and that wasn't enough)

If I had to do it again, I'd go with what the majority said here - around 425 whp


note: I'm on stock rear end. 8.8 with 3.55 on the way, will update

tbkonwso 03-21-16 12:45 PM

i daily drive my fd with 2-3 track days in a year, car only makes 380 with a cam. im aiming for 430-440 hopefuly after more mods. i think that a 450hp with semi r compound tires like nt01 or r888 would be the perfect fun street car.


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