TTS Supercharger development for RS4

[HYFR]

doug, it looked VERY fast coming into camp corner

[Doug_S2]

Excellent results Doug. What do you believe to be the reasons on why it doesn't produce as much Torque as the S5 you have developed, 617 vs 651? Is that just down to mapping and you are still tweaking to get more torque out of the RS4?

The S5 revs to 7k and the rs4 revs to 8k(ish), and becasue the charger has a maximum safe rpm to rev to, you have to gear it(with the pulley size) to be on that limit at your peak revs. Becasue the rotrex boost is proportional to revs, and the rs4 has to rev higher you open up the revs you have and so lose some lower down torque compared to the S5. The other thing is they have different cams and exhaust manifolds.

[P_G]

Should have worked that out for myself really, thanks anyway. Just need to save up now. How long do you intend to run the kit for and are you doing monitoring tests on the car during that time for durability / wear & tear?

[Doug_S2]

We are monitoring. We have a data logger that we are wiring up this week (i never had time befor ethe weekend) to monitor lots of temps and pressures. The car is going to the nurburgring this week for a few days to test it. Oil samples before and after will be sent to be monitored.

[RS4POWER]

Doug- Looks like the tq limiter is back in play? If so, I don't blame you guys trying to protect the drivetrain..

Did you guys upgrade the lwfw/clutch?

Impressive results! Keep up the good work!

[Doug_S2]

There is no torque limiter. This supercharger kit is a centrifugal/rotrex style so the torque curve is rising. The screw/roots type give more of a flat torque curve and slightly higher at low revs. This style is so efficent instead of keeping torque flat it rises at high revs. This charger is going to be less abusive on the clutch so a good stock clutch would be ok if driven sensibly as torque is always progressive.

[JackS4]

How does the charged RS perform side by side with the charged S4 ? Does the extra torque in the S4 give it an edge?

J

[klauster]

Is this another £20k kit?

[Doug_S2]

£10900+vat for the RS4 Supercharger kit which includes the 2 uprated hi pressure fuel pumps.

[adsgreen]

There is no torque limiter. This supercharger kit is a centrifugal/rotrex style so the torque curve is rising. The screw/roots type give more of a flat torque curve and slightly higher at low revs. This style is so efficent instead of keeping torque flat it rises at high revs. This charger is going to be less abusive on the clutch so a good stock clutch would be ok if driven sensibly as torque is always progressive.

Just to put this into context I uploaded Doug's dyno plit into my sim software and it reckons for a stock B7 RS4 the optimum method of launching the car is a dumping the clutch at 6400 (resulting in a 0-60 of 4.56 and 0-100 of 11.10. For the TTS/MRC car it's calculated the best is dumping the clutch at 1800 rpm (3.45 to 60 and 7.49 to 100).
It may be a little off with the centrifugal supercharger but the graphs seem to match the dyno plot.

[Stoffle32]

around the same price as the APR kit, guessing that does not include instillation?

[ROTREXPOWER]

Unfortunately, but fortunately we make so much power we need the pumps. Without the pumps we would be limited by about 80+bhp, we could only get 570 bhp and then leaning out to much, now we can run 660 on 102 octane with no problem. The good thing is that we have analysed the pumps and feel we can make the parts in the UK at a much better price and so keep the overall price down a little. Dougs getting the clutch in my S5 over the next week, then after bedding in we will try some 0-60's and put the car on some independant dyno's.

[P_G]

Are you going to sell this exclusively through MRC or can those handy enough purchase to DIY install?

[S4Player]

So is this the 'finished article' Richard with regards to the rs4 kit? I said to Doug with more torque I'd consider keeping my b7, Doug/Richard what boost are you putting out to make these numbers?

[Doug_S2]

You can buy the kit to DIY fit yourself.

This kit runs 14psi Danny. There is a 2 year parts warranty on the kit so you cannot overspin the charger to give more sooner - you could use a diffrnet pulley if you dropped the rev limiter though, if torque was more of a priority.