PARR 3.9 GT3 Conversion - Page 2 - 911/Carrera GT - PistonHeads UK

Interesting article in GT Porsche magazine this month. Features a 997.1 GT3 with a 3.9 ltr engine conversion to give 450BHP and 314LbFt torque. Article states.... New piston and liner set that increases the stroke by 4mm to 104mm. The bore is unchanged from the standard 3.6 at 76.4mm. Compression ratio rises rom 12 to 13:1. The article states that the standard titanium conrods have been retained but lighter ones can be specified. This conversion is completely reversable to take the engine back to a 3.6 if you want to. Price is listed at £12500 odd (plus the VAT) which is almost half the price of the Sharkwerks 3.9 conversion .... I think the Sharkwers conversion involves a re-bore of the block and gives around 500BHP but dont know for sure

Ooooo - when I first read this I saw 3.9 and cost £12500... That doesn’t sound too bad... Then I saw 450 BHP!!!!!! WTF!!! You can get 435BHP with an exhaust, flywheel, air filter and remap for about £3K Parr emptying pockets again...

Parr are the most expensive of the expensive I found.

mrdemon said: Parr are the most expensive of the expensive I found. 100% agree... Nice chaps but just like to pull your trousers down a bit too far...

Suprised me they are only making 450hp. I know of a 996 3.9 conversion which makes 470hp. I wonder what's holding this convertion back?

Had a service there the other week. Not impressed at all...

Suprised me they are only making 450hp. I know of a 996 3.9 conversion which makes 470hp. I wonder what's holding this convertion back?

996 3.9 v 997RS 3.6 http://vimeo.com/m/8822161

There is a lot of anti PARR sentiment on this thread...

keep it lit said: 996 3.9 v 997RS 3.6 http://vimeo.com/m/8822161 Afternoon Ade

I raced against a couple of 997 cup cars with that conversion in GT cup driven by Donovan and Hogarth. Along the Rivett straight they pulled out 100m on me. At the time, the championship was run on power to weight. After practice I went to see my engineer and said 'Mike and Paul are running a lot more power than us'. 'I know' he said 'we built the engines'. I didn't bother protesting - it was a non championship series at that time and I wasnt that bothered. Carerra cup was more important to us. Could out quailyfy them but in a race situation, their power realy told as my tyres went off. Devistaingly effective upgrade for the race track - Cant see the point on a road car though

993rsr said: Afternoon Ade Good afternoon JC

V8KSN said: Interesting article in GT Porsche magazine this month. Features a 997.1 GT3 with a 3.9 ltr engine conversion to give 450BHP and 314LbFt torque. Article states.... New piston and liner set that increases the stroke by 4mm to 104mm. The bore is unchanged from the standard 3.6 at 76.4mm. Compression ratio rises rom 12 to 13:1. The article states that the standard titanium conrods have been retained but lighter ones can be specified. This conversion is completely reversable to take the engine back to a 3.6 if you want to. Price is listed at £12500 odd (plus the VAT) which is almost half the price of the Sharkwerks 3.9 conversion .... I think the Sharkwers conversion involves a re-bore of the block and gives around 500BHP but dont know for sure It'll be the stroke that remains unchanged at 76.4, but the kit consists of new pistons & liners which take the bore to 104mm (13:1 compression would indicate it's probably a Capricorn piston & liner kit). One of the strengths of the Mezger design is the ease with which the pistons & liners can be changed: no "rebore" required. To get near to what SW claim to get on power, you need to change the cams & exhaust at the very least; Parr are getting about what you'd expect power & torque wise without making major changes to injectors, ECU replacement (not just a remap) & exhaust. BTW, I suspect "lighter conrods" just means the latest revision of 997 Cup rods which save a massive 3 grams off the 997.1 rods - at a cost of £800 per rod.

I'd suspect the difference is probably a little smaller if both run in the same dyno. Horses seem to be a little smaller stateside ;-)

ArcticGT3 said: I'd suspect the difference is probably a little smaller if both run in the same dyno. Horses seem to be a little smaller stateside ;-) The other possibility is that Americans are known to often not be averse to running rather fruity high octane race fuel in significantly tuned cars. A little checking (and MON to RON conversion) indicates that they can get unleaded brews equivalent in our measures to about 109 octane. That may or may not factor into claimed dyno numbers... ?

keep it lit said: 996 3.9 v 997RS 3.6 http://vimeo.com/m/8822161 Cracker, good to see Mike having a go !

DiscoColin said: The other possibility is that Americans are known to often not be averse to running rather fruity high octane race fuel in significantly tuned cars. A little checking (and MON to RON conversion) indicates that they can get unleaded brews equivalent in our measures to about 109 octane. That may or may not factor into claimed dyno numbers... ? On a F/I engine it can make a huge difference (if the ECU is mapped to take advantage of it) but on a N/A engine it wouldn't make much difference even with a new tune (save for maybe absolute extreme conditions - like a track day in 40C heat) where it would fight off The ignition being retarded.

nxi20 said: It'll be the stroke that remains unchanged at 76.4, but the kit consists of new pistons & liners which take the bore to 104mm (13:1 compression would indicate it's probably a Capricorn piston & liner kit). One of the strengths of the Mezger design is the ease with which the pistons & liners can be changed: no "rebore" required. To get near to what SW claim to get on power, you need to change the cams & exhaust at the very least; Parr are getting about what you'd expect power & torque wise without making major changes to injectors, ECU replacement (not just a remap) & exhaust. BTW, I suspect "lighter conrods" just means the latest revision of 997 Cup rods which save a massive 3 grams off the 997.1 rods - at a cost of £800 per rod. Thanks for that explanation Nick I must admit, I like the idea of 500BHP in my car but to be perfectly honest, I dont think it needs any more power! Certainally not for the road anyway and thats where mine spends 99% of its time. It mine was tracked as much as yours I think I would go for it! Have you ever been tempted with a 3.9 conversion?

nxi20 said: It'll be the stroke that remains unchanged at 76.4, but the kit consists of new pistons & liners which take the bore to 104mm (13:1 compression would indicate it's probably a Capricorn piston & liner kit). One of the strengths of the Mezger design is the ease with which the pistons & liners can be changed: no "rebore" required. To get near to what SW claim to get on power, you need to change the cams & exhaust at the very least; Parr are getting about what you'd expect power & torque wise without making major changes to injectors, ECU replacement (not just a remap) & exhaust. BTW, I suspect "lighter conrods" just means the latest revision of 997 Cup rods which save a massive 3 grams off the 997.1 rods - at a cost of £800 per rod. Thanks for that explanation Nick I must admit, I like the idea of 500BHP in my car but to be perfectly honest, I dont think it needs any more power! Certainally not for the road anyway and thats where mine spends 99% of its time. It mine was tracked as much as yours I think I would go for it! Have you ever been tempted with a 3.9 conversion?

V8KSN said: It mine was tracked as much as yours I think I would go for it! Have you ever been tempted with a 3.9 conversion? I did it nearly 2 years ago mate. It's done 36K miles since then & is going strong. Keeps up with 3.8 GT3s / RSs on acceleration even though they've got the lower gearing. Gen2 gearbox is the next upgrade I think... I did try the Cup CWP conversion for a year before rebuilding the engine but tbh I couldn't live with it on the road. I'd say on track it just about evens out the performance between a 997.1 with the Cup CWP and my car with "stock" gearing.

nxi20 said: I did it nearly 2 years ago mate. It's done 36K miles since then & is going strong. Keeps up with 3.8 GT3s / RSs on acceleration even though they've got the lower gearing. Gen2 gearbox is the next upgrade I think... I did try the Cup CWP conversion for a year before rebuilding the engine but tbh I couldn't live with it on the road. I'd say on track it just about evens out the performance between a 997.1 with the Cup CWP and my car with "stock" gearing. Awesome! Who did the work? PARR? Have you got a link to a build thread anywhere, I would be very interested in reading it. Cheers.

nxi20 said: ... I did try the Cup CWP conversion for a year before rebuilding the engine but tbh I couldn't live with it on the road. Out of curiosity, what didn't you like about it?

mrdemon said: Parr are the most expensive of the expensive I found. Go into any dealings with them with your eyes peeled. I can't be bothered to go into the details of my dreadful experiences (plural) with them, I have neither the time nor patience to explain why they were very lucky that my time is better spent elsewhere than launching a legal attack on them.

Slippydiff said: Here : http://www.911uk.com/viewtopic.php?t=69769&pos... Evening Nick, Ade, John. Thank you, I'll grab a glass of wine and get comfortable

993rsr said: Afternoon Ade Them zanzibar cars are not so fast,i hear the exhaust is something special now.;)

seawise said: mrdemon said: Parr are the most expensive of the expensive I found. Go into any dealings with them with your eyes peeled. I can't be bothered to go into the details of my dreadful experiences (plural) with them, I have neither the time nor patience to explain why they were very lucky that my time is better spent elsewhere than launching a legal attack on them. Similar experience , quoted price tripled on engine remap without consulting me first. Be careful !

braddo said: Out of curiosity, what didn't you like about it? It raises the revs by ~12% over the standard CWP gearing for any given wheel speed. That means that at 85mph (pretty much my minimum cruising speed on a m/way) you are sitting pretty near 4K RPM, 100 is 4.6K. I also found you were a lot busier changing gear and in many corners you either ran out of revs part way round or you didn't have the grunt in the first part of the corner because you were in a higher gear to cope with running out of revs in the second part. I think the Gen2 RS box is looking like the ideal compromise of a cruising sixth and slightly lower & better spaced ratios in the lower gears compared to my 'box.

V8KSN said: There is a lot of anti PARR sentiment on this thread... Speaks volumes really... They have a great rep and do really well in race - just (seemingly) unnecessarily expensive. Still they have to fund the race program somehow!

nxi20 said: It raises the revs by ~12% over the standard CWP gearing for any given wheel speed. That means that at 85mph (pretty much my minimum cruising speed on a m/way) you are sitting pretty near 4K RPM, 100 is 4.6K. I also found you were a lot busier changing gear and in many corners you either ran out of revs part way round or you didn't have the grunt in the first part of the corner because you were in a higher gear to cope with running out of revs in the second part. I think the Gen2 RS box is looking like the ideal compromise of a cruising sixth and slightly lower & better spaced ratios in the lower gears compared to my 'box. Thanks.