9sec9 and I have been talking about this subject for the past few days. I kmow we can hit our goal of 11.50 with the stock exhaust, but we have been considering other options. I hate the noise and reliability issues of most 3" systems and don't want one on my car. We are looking at building our own system and had meetings Friday with some of the best Fab/Exhaust guys here in Indy. There is only one way we will do this, it will be not be a 3", it will be quiet, Mil.Spec 100 cell catted, and strong. We have found that the stock exhaust with the factory cat works fine at our power level, but there is always room for improvement. We are running 26.5 psi on Shell or BP 93 pump gas with my street tune without any issues to date. I know there is more left in the car as it sits, and I would like to max it out before our next mod, going to E85 in the coming weeks (insert Fathouse happy dance here). It's going to be a busy next 10 weeks with plenty of testing and new parts development, as always we will post all of our findings. Thanks for following, Indy

 

We went back to the track tonight for some fun for a change. It was a warm evemimg to hang out with the Indy HP guys and EVOVIII200 from EvoM. With the same setup as before, two mods and a 9sec9 tune, we just played around with tire pressure and did not touch the tune. Started off with 32 psi all around and ran an easy 12.001 @ 113.88 for an A to B shakedown run with the higher tire pressure. Then with the same tire psi we ran a 11.952 @ 112.39 slipping the clutch a tick too much. For the last pass I dropped the tires to 30 psi all around and backed off the MBC 1/4 of a turn. We ran a soft 11.848 @ 115.14 with a bit of knock due to me forgetting to lift on the 3-4 shift. The conditions tonight were worse (temp/headwind) than when we ran the 11.83, but we don't pick and choose the days we run, if the track is open we go. Tom's tune was spot on as usual even with bad air this thing was moving. Thanks again Tom, it's nice to go to the track and not worry about how this hot rod is going to run. I know as long as I keep improving my driving this car will run a low .70 as is. Indy

 

subscribed

 

good driving Indy!

 

nice to see your progression indy

 

Thanks EVOVIII200 for showing me the video between the runs , it helped me decide to drop the tire psi and boost. Good seeing you again . Indy

 

What were the 60 ft times on the runs?

I'm not clued up on tire pressures but if this drag radial is soft and looks a bit like a full slick, isn't 30+ psi just way too much pressure? I mean that is what you would run on the street isn't it?

 

I think he went out on lower pressure the first time out and likely had some bogging issue?

The higher tire pressure was probably to get a small amount of spin out of the tires.

If the tires are very grippy, it takes quite a bit of HP/Torque to get a good launch at full traction on an AWD with (practically) full slicks.

 

03 once again your right. We have been trying different tire pressures to see what works with my car. With limited HP, a sticky tire, and a light flywheel/clutch combo, there is a fine line to launch this car.

We ran around 30 psi last outing when we ran the 11.83 with a sticky track and had too much grip. Last night the track had less grip, and we started out with 32 psi to get some wheel speed. Once we made the shakedown pass and the first serious run we felt the psi could come down to add grip without having to too much rolling drag. We were just adjusting the car to the track condition.

The 60's were still soft with 1.713 being the best for the night. It's taking much longer to get the feel for how much or little clutch is necessary to launch the car for a given condition, but were learning as we go.

 

I see well that sounds promising that they have more grip than you have power at 30 psi! This does seem puzzling though because I don't think it is an unusual occurance for an Evo on street tires to cut a 1.7 or 1.6 60 ft with minimal mods is it? I know for the earlier Evos which I'm more familiar with it wasn't.

Is it uncommon to see an Evo 8 or 9 cut a 1.6 on street tires?

 

crcain, what you're missing here is something I've stated on several occassions. The 60' time is absolutely only 1 part of the contribution that a tire makes to the run. The weight and the rolling resistence both contribute to the entire run. Since we've obviously had launching problems with the new clutch and the new tires, we STILL been able to increase the mph substantially with the same tune and car, while at the same time, lower the ET from 12.01 to 11.83. We've now also had 4 or 5 runs below our previous best on the BFGs, all of them in the 11's. That kind of proves once and for all that anyone looking at 60' times only has no clue as to how important other factors really are. These tires, due to being radial, contribute to the ET/MPH by the engine not having to 'PUSH' 4 nearly flat tires for a 1/4 of a mile. That's energy savings. As the MPH goes up, the ET will also drop, which it has.

Indy made several, several runs in all configurations prior to us testing the new Hoosiers. At ORP, the BEST mph was only 113.xx if I recall correctly. We then put the tires on the car, went to Muncy and 1st pass recorded it's best ET AND MPH of 12.00 @ 116.58. Then went back to ORP and have backed that up with several runs in the 115+ and 4 or 5 ET's in the 11.8's and 11.9s. The exact same parts, the exact same tune, with the normal 'conditions' tweeking' as I've always done. Now, as Indy gets the clutch 'feel' down and the 60's drop, I would be looking for solid 11.7's out of this MBC, airfilter and tuned car. That's pretty clear as to the benefits we've seen while using this tire. Lots of bite with a new clutch feel is what we're working through now.

 

Yeah that is a good point about how a lot of us, me included, might be focusing on 60 ft's too much.

That said, it doesn't sound like you guys are sacrificing grip to achieve higher tire pressures, which gets back to my point about why the car is not cutting better 60 fts. But I guess the answer is you are working on it.

I just would have thought grip + good clutch + 11 sec Evo = 1.6 / 1.7 60 fts all day long. Might be an incorrect assumption though.

 

No doubt, a good 60' is worth at least 1.3-1.5 times the 60' improvement. 1.6 dropped to 1.5 will generally give .15 improvement on the 1/4 ET, with about 95% of that coming in the 1/8th ET. So, consider that if MOST of the improvement for the 60' shows up in the first half, something could ALSO help the back half. That's the weight and rolling resistence.

 

The car would 60' better with more power. Like if Indy would take the cat off of it, and put it on e85.

Tom, my car will be on the road soon sir.

Fathouse

 

The car would 60' better if you were driving it