You worked at Honduh?

LIES. lies and slander.

Don't want to keep junking up dowards thread, but the time is quickly approaching that I must pull the trigger on ST5 power. Leaning rotrex, but curious how much power I could expect from square top / cams on a BP4W w/ BP5A and VICS mani that currently makes 142whp on e85. Trying to avoid revving to the moon and if I send the head off for work similar to what doward did, well, that adds up to rotrex money real quick. 257mm template is still unlocked at 2400lbs, so that makes life slightly easier. No splitter means about 158whp avg at 2400lbs or 153whp with splitter.

Based on Emilio's stats N/A with headwork, cams, healthy bottom end is good for 180ish on E, but based on my current HP I don't think I can expect anything near that. I'm having a hard time believing square top / cams is going to pickup ~20whp, but have been wrong before. Thoughts? I know rotrex has its own bag of issues and is gutless, but should be able to run some pretty high peak whp. Combined with 6 speed could be a lot of fun, but if I can stay N/A without breaking the bank, I'm all about it.

Your current 142whp is very fast at 2250. I raw timed the IS300 that won ST5 Champs the only time we raced each other. (Yes, I cherish my 2nd place non-win but taking the track record. Don't judge me.)

I view the build options as:

A. 142/2250, 226mm, 205 R7s on 8", +/- splitter, (225RC1 on 9" clears template and gets you a free splitter, or pure P:W bump with the .5 100tw credit now)
B. 159/2400, 257mm, 225 R7s on 9", +/- splitter. (245RC1 on 10" clears template and gets you a free splitter, or pure P:W bump with the .5 100tw credit now)

Either version is allowed an OsGiken for free, which is basically 1 second at any track vs a Torsen, more at some.

I think the "B" build is faster anywhere, and way better nationally vs other platforms, but it requires $$$ in the motor and running heavy. If the car is 100% only for use in NASA, thats the way to go. Any other usage, or HPDE, TT, fun days makes the super lightweight 2250 build really, really fun to drive.

My engine should make enough to cover running at 2450lbs with OE cams(BP5A) and a junkyard block. If not, my options are cams and new lifters, or take the .1P:W penalty and run 2400lbs.

I wrote this for another discussion. Just some general observations.

By running a spoiler, wing or airdam, you forfeit the .4 credit for BTM aero. Aero is not free.

A splitter costs another .5 P:W, bringing the 'cost' of balanced aero(wing + splitter) to .9lbs per horsepower.

Adding aero costs more than having oem A-arms, for example.

Running heavy benefits your ratio, thanks to the comp weight adjustment chart. It is easier to add weight, while benefiting your ratio and staying in the lower class. Meaning, you're more likely to be at the pointy end thanks to comp weight adjustment factors if you add the ballast and run 6.

No doubt. My car as it sits needs ~30lbs of ballast (2460lbs) to be optimized on 93 (136whp peak / 131-132avg) for 6. That's the obvious easy button, but I'd be running ST6 by myself vs what's shaping up to be a fairly large ST5 class. Car is only used for NASA and obviously about to be removed from street duty, so I'd like to make it more fun in case I decide to hit the occasional DE anyways. Obviously I can stay right where I'm at, cage the car, start gutting and aero for lightweight ST5 and ballast up for ST6 if the class gets some attention. Just sounds fun to run the car at current weight, mo' powah, aero, and 225 hoosiers.

Or take my caged 94 and quickly run out of excuses entirely.

That's not off the table, we can chat about it over beers when I come to get the pupper next weekend. If I sell my car and get blue I'd have a hard time not taking it straight back to SM for the huge fields, haha.

Edit: Wrong freaking thread.

GAH. Stupid "related threads" feature.... Oh well, i'll leave it.


Nothing super sciency or conclusive, just keeping notes here. Confirming some assumptions.

Car is about 100lbs lighter than it was in February.
Still ST5 legal(14.66 adj) at 2150/144 peak(~140avg). Room for more power, which was the goal.

225 Maxxis RC1 (Stickers)
2:01.9 CCW

205 Hoosier R7 (same set I raced on in 2016, TT'd on in Feb 18, probably 20+ cycles)
2:03.07 CCW


So, sticker RC1 in the same "real" size(both tires are 224-226mm wide) are faster than cycled R7. Duh?
Weather, track conditions, cycle count, weight reduction and 4whp worked out to be worth about 3.7 seconds on 225/45 RC1s.

That's some great data on RC1 vs. R7. I'm hoping a 245 RC1 will narrow the gap slightly, doubt it'll make it up entirely.

I'm under no allusions that even a non-existent 295 rc1 would hold a candle to fresh 205 R7's. I can get 8-10 cycle SM7 take offs for 200$ ish a set. I can get 6-10 more cycles out of them till they cord. I'll give up 1-3 seconds a lap and run the 245 RC1 just so I don't have to swap tires like a madman. Seems like 30 heat cycles for 600$ is what I could expect out of the RC1 and puts the costs in the same ball park.

Yea.

They still have a finite life span. I can stretch them out to 18-20HC when I'm only running R7s for an extended run of races/events, but when I switch back and forth between several different tires, old R7s feel like crap. They get really razor edgy and when they start sliding, you're gonna be slidin for a while. They also take forever to warm up when they're cycled and worn. They run so cool at full tread depth, that when they're worn down halfway, they're hard to bring up without weaving(which is becoming no bueno with many orgs) or waiting for 2 laps.

Kinda off topic to ST5 and the tires but why are racing organizations having issues with weaving on outlap to bring up to temp before start off race?

Because dipshits don't watch for the yellow flags to drop then weave into a car going 50mph faster who is watching for the flags.

Thinking about running ST5 for a little bit while getting other parts together... leaning towards the 2450/158 build with airdam/splitter/wing and 225 R7's.

I saw that a 245 RC1 on a 10" wheel fits the 257mm template? Anyone know if a 225 R7 on a 10" wheel also fits? I figure if a 205 RC1 can fit on a 9" wheel then a 225 R7 will definitely work on a 10" as far as ease of use goes for being able to have all one wheel size...