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MG MGF Technical - TB Questions

I have a few questions about fitting a Trophy TB to 'normal' F's, as I want to, but want to know what I'm going to really get out of it and will it hurt my Transmission (Stepspeed)

1. Does anyone know for sure what the BHP gain is by fitting a Trophy TB to a standard 1.8i/Stepspeed, and again what the gain is with a K&N fitted as well?

2. Is the gain in BHP likely to prematurely damage my Transmission; seeming as MGR chose not to upgrade the Stepspeed TF to 135BHP, even though the max Torque is still the same. (thought it was the torque which limited the power through the transmission)

3. Generally does this mod really offer much if you already have a K&N fitted? - Is it really worth it?

Cheers
Nigel

Nigel Kidd

Good questions there Nigel. In essence, most we can not answer until we've done some comparative RR tests on the 1.8i, with and without the K&N.

My *guess* would be that the combo would result in about + 12 bhp- but as I say, this needs to be confirmed.

You're absolutely right, for some reason the Selespeed TF has not been upgraded to 135 spec. Perhaps there are other reasons for this other than the increase in power. One of the quoted reasons you don't find the Selespeed on the VVC is that the gearbox cannot take the engine speeds that the VVC motor is capable of. Does anyone know what the rev limit on the new 135 is? The other potential reason for not fitting the 135 with Selespeed is the nature of the power delivery- we've heard already that idle is a bit lumpy (thanks to the new cam profiles), so perhaps the torque curve is not entirely suited to an automatic transmission.

In short, the answer is 'I don't know'- but I am sure that there is someone out there who does... Perhaps Dr Dave can seek the transmission technical data out for you?
Rob Bell

I have just checked and it looks like the max BHP figure for the TF135 is over 6000 RPM - This would account for this engine not going into the Stepspeed as it is limited at 6000! Now the question comes; would fitting a new TB with K&N put the max BHP outside my rev limit?

Nigel
Nigel Kidd

Rob , put those Alfa brochures away! The Stepspeed is governed to about 6500 rpm as constant higher rpm is supposed to cause damage to the transmission, however we recently had a customer from Germany with a Stepspeed with 7000kms on the clock, he had our big valve head with higher lift cam(inlet only) that drove superbly, he sent us a fax saying that the power delivery was fantastic and that at 6000rpm he was showing 210kph with more to go.Tickover was as normal. If driven with consideration (;-))then the gearbox should be OK.
The Trophy throttle body on a VVC may reduce torque lower down but give a higher top end potential on the 1.8i the torque losses, if any, may not be as noticable due to the inlet design it should help the top end breathing if combined with a suitable induction kit.
Mike.
Mike

This thread was discussed between 05/02/2002 and 06/02/2002

MG MGF Technical index

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