Guys, our VR4 rally car in SA ( Gary Brown/Mike Dale ) is about to get an engine freshen up ready for the up coming ARC "Scouts SA Rally" round in Adelaide. It has had a long and abusive life, and was originally built by Dasher Williams side by side to Ross Dunkertons Ralliart Gp A VR4 in 1992.
Currently, it is one of the top 3 seeded cars in SA ... and certainly the car that most competitors know they have to beat if they want to win. In fact, it is virtually unbeatable in the Forests, and it is only on the fast shire roads that late model Subarus and Evo's tend to do better ( aero and rear suspension design ??) Our philosophy tends to be "win it or bin it ", and we dont like to come second ! For a fairly rough old VR4, it is very quick.
It runs a 8.5 :1 compression motor on E85, ralliart ( spec unknown) cams, ECM Link and a still standard AFM, and makes around 190 kwaw at 4000 rpm on a Dyno Dynamics dyno, at about a 23 psi boost peak.
I have never managed to make the engine knock on E85 fuel, so I decided to up the compression to utilize the full capability of ethanol based fuel. Other people in the States must have been thinking the same... JE Pistons list in their 4G63 catalougue an E85 spec piston... it is a flat top piston giving 10.0 : 1 compression. We also CNC ported ( mainly exhaust side) the head that was fitted with 1mm oversize Ferrea valves. Flow picked up around 12 %. The cams being used are Kelfords restrictor grind, which are essentially 258 inlets and 264 exhaust spec.
The engine is being fitted at the moment, and dyno work hopefully in a week or so. I will replace the standard VR4 airflow meter with an Evo AFM, as I have had good 10 % torque gains on our sister car last week, using the larger Evo AFM. The torque definitely holds on for another 500 rpm, before dropping ... I was slightly surprised, as I thought the 34mm turbo restrictor would have been the limiting factor. I suspect the mapping will now involve a rethink on the spark advance curve due to higher compression. Gary and I are looking forward to a lagless turbo engine on the gravel... not that was lacking before. The boys reckon it will be evolving from a torque monster into a torque Godzilla. I suppose it will be a test of the Dog box and the drivetrain ? Should be fun any way .
Cheers Mike
Currently, it is one of the top 3 seeded cars in SA ... and certainly the car that most competitors know they have to beat if they want to win. In fact, it is virtually unbeatable in the Forests, and it is only on the fast shire roads that late model Subarus and Evo's tend to do better ( aero and rear suspension design ??) Our philosophy tends to be "win it or bin it ", and we dont like to come second ! For a fairly rough old VR4, it is very quick.
It runs a 8.5 :1 compression motor on E85, ralliart ( spec unknown) cams, ECM Link and a still standard AFM, and makes around 190 kwaw at 4000 rpm on a Dyno Dynamics dyno, at about a 23 psi boost peak.
I have never managed to make the engine knock on E85 fuel, so I decided to up the compression to utilize the full capability of ethanol based fuel. Other people in the States must have been thinking the same... JE Pistons list in their 4G63 catalougue an E85 spec piston... it is a flat top piston giving 10.0 : 1 compression. We also CNC ported ( mainly exhaust side) the head that was fitted with 1mm oversize Ferrea valves. Flow picked up around 12 %. The cams being used are Kelfords restrictor grind, which are essentially 258 inlets and 264 exhaust spec.
The engine is being fitted at the moment, and dyno work hopefully in a week or so. I will replace the standard VR4 airflow meter with an Evo AFM, as I have had good 10 % torque gains on our sister car last week, using the larger Evo AFM. The torque definitely holds on for another 500 rpm, before dropping ... I was slightly surprised, as I thought the 34mm turbo restrictor would have been the limiting factor. I suspect the mapping will now involve a rethink on the spark advance curve due to higher compression. Gary and I are looking forward to a lagless turbo engine on the gravel... not that was lacking before. The boys reckon it will be evolving from a torque monster into a torque Godzilla. I suppose it will be a test of the Dog box and the drivetrain ? Should be fun any way .
Cheers Mike
