Where do I start this thread......so many things on my mind, too many after thoughts.

Let me start by first saying the best our EVOX ran on stock engine/head with our Stages 1-3, plus ported exhaust manifold, stock 02 housing ported, Cosworth cams, Blouch Dom 2.0 and pump gas was 11.71 at 124.xx mph. The car would not leave the line very hard back then and we never figured out why, it was also out of gear to finish the 1/4 mile in 4th gear.

Flash forward to our winter project.

BR Stg 3 shortblock, BR Stg 3 head, BR T3 turbo kit with Blouch GT600R turbo and a final drive change to drop the RPM.

The result of these changes were GREAT power on 93 octane, here is one of the dyno graphs from the initial tuning. I was actually able to hit 525 whp with the current tune that is in the car:



Two weeks ago we took the car back to the track, Kevin drove, I drove. Both us of turned 12.33 in the car, the car would only bog and not leave the line. Kevin being the excellent driver he is noticed the two step was at 5500 rpm. Interesting as I had it set to 6800, after a few attempts I realized something in my ROM was wrong and it was not adjustable. That explains it never leaving the line well. After posting the problem I was helped by a number of people in the stock ECU section and the problem with the two step was fixed.

Last night I took the car out to the track by myself. I made three passes, the best of which was an 11.67 at 126.23 mph, the best 60' was 1.77 with a slight bog half way through the clutch release. I'm no Pro driver and that's why I have Kevin and Trent drive for me. I am capable of running a mid 11 second 5 speed about as quick as anyone though, it's when they are really fast that I can't compete. So I am not blaming the performance on my driving as it wasn't really that bad. No powershifting but shifted as quickly as I am capable of. The car is at absolute full weight and had about a 1/2 tank of whatever pump gas was put in it last, 93 octane from somewhere. 29 psi peak boost, 0 knock counts on the entire run. Injectors are at 97% duty cycle, I'm running ID1000's.

So on to my after thoughts.

The stock gearing in the EVOX combined with the stock shortblock and a good amount of power sucks, the car simply runs out of gear before it can finish the 1/4 mile, which was the case last year. In my big list of desires was to fix the RPM issues and install a different final drive. My problem was my thought process as I was not considering at the time I was going to be building an engine that would run to 10,000 rpm and putting a large turbo on it. This combination doesn't work, never has.

The gearing in the car is so tall now that it keeps the car out of it's power range. If you take a second to view the graph the car makes very good peak numbers. The problem with the EVOX's are I have not seen one personally that has a BIG FAT power band, so it has to be run high in RPM and when it shifts it drops back out of power. Not a good drag car.

The gearing is so poor in the car now that I do not need to shift to 4th gear until the finish line is coming up and I'd guess after 1,000 feet. The EVOX stock with 400 whp is in 4th by the 1/8th mile. Same story for the EVO8-9's.

The interesting thing is the top end power after the 1/8th mile and this is where the car feels freaking strong. At the 1/8th mile the car is running only 91.56 mph by the finish it's gained 34.67 mph, this is HUGE in the back half of the track.

I am not gutting this car and I am also not trying to turn it into a drag car. I do feel though that drag times/mph are a very good indicator of how a car is working and the power it makes. In this case the combination of the tall gear and the large turbo with a peaky power band just doesn't work.

Now for my dilemna, to change to the stock gear ratio again or to drop down to a stock appearing turbo again.

Anyone looking to trade a fresh EVOX trans with the tall final drive and some cash for their stock transmission?

Our new best for reference is:

1.777 sixty foot
7.65 at 91.56 at the 1/8th mile
11.676 at 126.23 at the 1/4 mile

 

Wow that's awesome! Keep up the great work! Hopefully with the final drive ratio fixed you can pull out some impressive times.

 

So with a bigger turbo you think the stock gearing is where it's at in other words? Just making sure I am following...and that a smaller turbo with more midrange would make better use of the final drive change?

I am glad with my build i decided Revs were the way to go for keeping it in 4th through the 1/4...looks like it will pay off.

Good write up DB, thanks for this.

 

Surely dropping back down to a stock appearing turbo would be easier to do than changing out the final drive. It would be nice to see your comparisons in that case from the GT600R turbo to something such as the Red while keeping the final drive.

Regardless of the outcome, this is all good information.

 

Great work David! when is the Bad Bish coming out to play?

 

I think most would-be Evo X parts buyers would like to see how the car runs with the stock gearing. Most people never mess around with that. Personally, if I were to change the gearing in my X, I'd want it shorter so the car doesn't feel so anemic in a regular off-idle start. That's when you feel the weight of the X the most to me.

 

do you thinkthat trans would work good with a stock turbo setup? Basically full boltons and a 2.0 sized turbo. I'm not looking to build a drag car, but i've always thought about the final drive to bring cruising down and still be able to autox every now and then.

 

Why not put some R&D into the TC-SST trans. in the MR/Ralliart. Crack it open, upgrade the clutch packs, tweak the TCU, and boom. A drag Evo that won't leave the power band. I make it sound easy, don't I, LOL

 

People are doing this...even with 500whp, the MR can't hit 11.0's. The TC-SST trans is not a smart idea if you want high HP or drag application. The simpler the better. Not to mention the enormous price tag to make it handle power in addition to the higher initial cost.

 

I have yet to see anyone figure out the TCU for the TC-SST. SSP makes clutch packs that can withstand 500+ torque at the moment. The last frontier is the TCU. Adding an improved mode, better than S-Sport mode in terms of clamping force and faster intervals of shifts, the TC-SST will do amazing things. The construction of this trans. itself has been proven to be reliable and durable already. The weak points are the clutches and the TCU maps.

 

NOOB QUESTION: sorry in advance for my lack of knowledge in this area

what if someone was willing to put in the time to change the gearing, like he did, and make 1-4 really short and good for racing, but make 5 really long so it would be good for highway driving/fuel economy? is that possible?

 

Yes, I think the gearing I have work work much better on a stock style fast spooling turbo.

The SST trans is interesting, putting time/effort/money into R&D for it is of zero interest to me. It's one of those things I'll wait for and get parts/programming as it becomes available. The market is WAY to small for one company to put any serious time/money into it.

Same goes with the changed gearing suggestion for 1-4 and 5th, HUGE expense in doing gears, market isn't there. We've sold 1 final drive in nearly a year.