4.7 Road Engine Results for APM Racecar
Discussion
Spent a great day with Andy (APM), Dom and Jay (TVR Power) and John Ravenscroft (the J in AJP V8 ,engine designer)!!!
The 4.7 had only run up to 5500 in 100 miles at Brands the week before to run it in and had a hard day from 9.30 until the final run at 5.45 yesterday evening!! We did 60 litres of Sunoco 102 Octane race fuel on the rolling road! Ouch ££!!
All numbers are at the wheels as required by the technical regs.
The purpose was to bring me in line with either the top power to weight allowed in Group 1 or Group 2, which with my cars weight equates to either 340 bhp at the wheels or 380 bhp.
On the basis that this is a stock road conversion using all the standard cams and bits except the 4.7 pistons and block bore, we had to run it up to see which way we were going to face, torque being an important part of the mapping but bhp being the class selector. Were we going to be short on torque and power and dial down to Class 2 or were we going to be able to push up into a competitive profile for Group 1.
We'd been in dialogue with the technical team for the GT Cup and basically our fate was in the hands of how the engine was going to perform.
It was soon apparent as the mapping started that torque was up significantly, 325 ft-ibs at 3000 rpm, then at 4000rpm the plateau starts at 365 ft-ibs all the awy to 5750.
After much deliberation we decided to go for Group 1, what's the point of not becoming a front runner when you have the opportunity, the handling has been significantly improved with various tweeks and some great help from Pirelli workng with Andy to get us on to the medium compounds, see the last story of the wishbones etc..
So the fuel was dialled in and the race mapping started, amazing to see what the MBE System can do when fully opened up by John, I was staggered by what they could adjust to map the best curves and to stay within the rules to comply.
The net result was a power curve which peaks at 379 bhp at the wheels at 6000 rpm and is within 20 bhp of this from 5250 to 7250. Rev limiter comes in at 7500 and the change light comes in at 6500.
Last year we ran at 330bhp at the wheels.
So what a result, remember the car runs cats now which restricts it a bit and has two boxes to get the sound down to below 105 dB. The only changes are ported heads, 4.2 breathing/inlets, bigger injectors and Andy's 4.7 litre conversion.
Have to say that this was a perfect result, I am happy to run with the Ferrari 430 GT's and the 997 GT Cup cars as long as we are now all on the same footing, this really makes it worth the while as I was getting a little frustrated coming mid pack.
So thanks Andy, Dom, Jay and John!
The 4.7 had only run up to 5500 in 100 miles at Brands the week before to run it in and had a hard day from 9.30 until the final run at 5.45 yesterday evening!! We did 60 litres of Sunoco 102 Octane race fuel on the rolling road! Ouch ££!!
All numbers are at the wheels as required by the technical regs.
The purpose was to bring me in line with either the top power to weight allowed in Group 1 or Group 2, which with my cars weight equates to either 340 bhp at the wheels or 380 bhp.
On the basis that this is a stock road conversion using all the standard cams and bits except the 4.7 pistons and block bore, we had to run it up to see which way we were going to face, torque being an important part of the mapping but bhp being the class selector. Were we going to be short on torque and power and dial down to Class 2 or were we going to be able to push up into a competitive profile for Group 1.
We'd been in dialogue with the technical team for the GT Cup and basically our fate was in the hands of how the engine was going to perform.
It was soon apparent as the mapping started that torque was up significantly, 325 ft-ibs at 3000 rpm, then at 4000rpm the plateau starts at 365 ft-ibs all the awy to 5750.
After much deliberation we decided to go for Group 1, what's the point of not becoming a front runner when you have the opportunity, the handling has been significantly improved with various tweeks and some great help from Pirelli workng with Andy to get us on to the medium compounds, see the last story of the wishbones etc..
So the fuel was dialled in and the race mapping started, amazing to see what the MBE System can do when fully opened up by John, I was staggered by what they could adjust to map the best curves and to stay within the rules to comply.
The net result was a power curve which peaks at 379 bhp at the wheels at 6000 rpm and is within 20 bhp of this from 5250 to 7250. Rev limiter comes in at 7500 and the change light comes in at 6500.
Last year we ran at 330bhp at the wheels.
So what a result, remember the car runs cats now which restricts it a bit and has two boxes to get the sound down to below 105 dB. The only changes are ported heads, 4.2 breathing/inlets, bigger injectors and Andy's 4.7 litre conversion.
Have to say that this was a perfect result, I am happy to run with the Ferrari 430 GT's and the 997 GT Cup cars as long as we are now all on the same footing, this really makes it worth the while as I was getting a little frustrated coming mid pack.
So thanks Andy, Dom, Jay and John!
That is some serious area under the curve! Extremely impressive to think that for the first 1 second of the race or so you'll not be at peak power. After that, looks like you'll have >360HP under your foot for the entire race!
When&where are the races? can we come along and support?
Stu
When&where are the races? can we come along and support?
Stu
www.gtcup.co.uk has all the details on it, we've entered all the GT Cup events except Oulton Park, so our first outing is 17/18 April at Silverstone supporting Formula 2. You are most welcome!
Oh and as it is a rolling start we'll be on the power all the way!!
Oh and as it is a rolling start we'll be on the power all the way!!
Edited by JonnyW on Friday 2nd April 17:38
JensenA said:
Jonny - Out of interest, what are the figures at the flywheel?
the general thought is you loose 17% to 19% through the driveline but it's all still a guestimate figure RWP Horsepower is the true figure ie real horse power,we did actually make more power on the r/road but backed it off due to the racing regulations(the chip is now locked to meet regs!)HarryW said:
very nice, that's some torque, good to see the worked 4.2 inlets flowing enough even for the 4.7ltr I bet it goes like stink.andy
APMAUTO said:
HarryW said:
very nice, that's some torque, good to see the worked 4.2 inlets flowing enough even for the 4.7ltr I bet it goes like stink.andy
I'll take mine up to Charlies before the end of the month, the monies on 465hp/410lbs but Jonnies must be near 450lbs which is the important bit.
APMAUTO said:
HarryW said:
very nice, that's some torque, good to see the worked 4.2 inlets flowing enough even for the 4.7ltr I bet it goes like stink.andy
A road car will have a better crack at the 500 bp but you'll have to strap on some big cans for track days!
JonnyW said:
.........It's a shame that the noise restrictions are really taking a grip on motor racing,.........
It's a great shame. The sound/noise of the cars engines are surely one of the biggest attractions of Motor racing. Can you imagine how dull it would be watching 20 Tesla's racing! Gassing Station | Cerbera | Top of Page | What's New | My Stuff