Silver C70 T5 - Manual - 400BHP

[theflyingbrick]

that's good news dave im well chuffed for you mate and look forward to seeing it running once more

[Wobbly Dave]

Certainly feels more genuine this time rather than just a bunch of expensive parts bolted together.

[graemewelch]

h 

Whats the standard compression ratio on the t5. Aet said nosh lost the bhp he would of gained on a flowed head cause he lowered the compresion

[p fandango]

h 

Whats the standard compression ratio on the t5

8.5:1

[Wobbly Dave]

8.5 to 1. With NA engines I'd agree - usually you want to raise the compression to get the maximum efficiency from the same amount of fuel. With forced induction can utilise the lowered compression to get more F&A into the cylinder to compensate - force the bleedin' stuff in & avoid det. which is why it is normally lower than NA engines for that reason.

[Jamest5r]

Going to be nice Dave run in by the end of March then and then go and get it properly mapped or were all going to gang up and bitch slap you

[Wobbly Dave]

Going to be nice Dave run in by the end of March then and then go and ...

break it again?

[claymore]

Compression has been lowered - 7.93 to 1

.

I don't quite understand the reasoning for this, unless your going to be running 30psi. Your car is going to be completely gutless before the turbo spools with a cr that low, can you explain exactly why the engine builder has suggested this (Alarm bells are starting to ring in my head) unless you're aiming for well over 500 bhp. and again, why would you not use NA cams if you're doing all this work?

[claymore]

8.5 to 1. With NA engines I'd agree - usually you want to raise the compression to get the maximum efficiency from the same amount of fuel. With forced induction can utilise the lowered compression to get more F&A into the cylinder to compensate - force the bleedin' stuff in & avoid det. which is why it is normally lower than NA engines for that reason.

Weare all aware that you need to lower the cr for a turbo engine, which is why the cr is lowered to 8.5 to 1, lowering it as low as you have has just killed any performance gains you may have had in gas flowing the head...I really don't trust your engine builder, does he normally work on Volvo engines?

[smithy]

Weare all aware that you need to lower the cr for a turbo engine, which is why the cr is lowered to 8.5 to 1, lowering it as low as you have has just killed any performance gains you may have had in gas flowing the head...I really don't trust your engine builder, does he normally work on Volvo engines?

S60r runs at 8 to 1 ratio and they run fine .and my v70 2.5lpt ran well into the 7s on the compression ratio and never a problem and it pulled very well .you can also map round lower compression wilst off boost to keep the torque up .

[stribo]

TBH off boost the S60R feels pretty sluggish, once on boost however....

[graemewelch]

TBH off boost the S60R feels pretty sluggish, once on boost however....

thats strange i thought it would of drove exactly the same as the t5. my engine is same as yours except 100cc smaller.

[claymore]

S60r runs at 8 to 1 ratio and they run fine .and my v70 2.5lpt ran well into the 7s on the compression ratio and never a problem and it pulled very well .you can also map round lower compression wilst off boost to keep the torque up .

But why do you need to lower it that far in the first place, I run 8.5 to 1 with no detonation problems, and if I did get close to the limit I would rather water inject it rather than compromise performance, seems like a huge backward step to me.

And I don't understand the bit I've highlighted in bold?

[jamesy12345]

But why do you need to lower it that far in the first place, I run 8.5 to 1 with no detonation problems, and if I did get close to the limit I would rather water inject it rather than compromise performance, seems like a huge backward step to me.

And I don't understand the bit I've highlighted in bold?

Somewhere between 7.0:1 and 7.9:1 compression ratio on his 2.5 LPT

[claymore]

Somewhere between 7.0:1 and 7.9:1 compression ratio on his 2.5 LPT

Still makes no sense, I see no reason to lower the compression that far: This from Garrett's own web site:


There are numerous factors that affect the maximum allowable compression ratio. There is no single correct answer for every application. Generally, compression ratio should be set as high as feasible without encountering detonation at the maximum load condition. Compression ratio that is too low will result in an engine that is a bit sluggish in off-boost operation. However, if it is too high this can lead to serious knock-related engine problems.

I can only assume that Dave is trying to go for well over 500 bhp

[WOODY T5]

Still makes no sense, I see no reason to lower the compression that far: This from Garrett's own web site:


There are numerous factors that affect the maximum allowable compression ratio. There is no single correct answer for every application. Generally, compression ratio should be set as high as feasible without encountering detonation at the maximum load condition. Compression ratio that is too low will result in an engine that is a bit sluggish in off-boost operation. However, if it is too high this can lead to serious knock-related engine problems.

I can only assume that Dave is trying to go for well over 500 bhp

because he is going to need col lol

[stribo]

thats strange i thought it would of drove exactly the same as the t5. my engine is same as yours except 100cc smaller.

But its a heavier car.

[graemewelch]

But its a heavier car.

cant be that much heavier. that probobly the difference between 2wd and awd. well have to try each others car if your at rolling road day. be intresting to compare the two

[stribo]

cant be that much heavier. that probobly the difference between 2wd and awd. well have to try each others car if your at rolling road day. be intresting to compare the two

Yeah, are you going to Uxbridge?

[V70 Graham]

Yeah, are you going to Uxbridge?

Keep up speedy, he's already paid his deposit !