850 t5 lowering compression

[graemewelch]

im just thinking out loud here. but if the compression was lowered on the 2.3 t5 would it make them safer to run higher boost on standard rods.

[Jamest5r]

im just thinking out loud here. but if the compression was lowered on the 2.3 t5 would it make them safer to run higher boost on standard rods.

Yep you can run higher boost, Smithy did it on his v70 by using s60r rods and pistons

[daza-b]

Would the block need boring out with s60r rods and pistons?

[graemewelch]

i was thinking about getting some decompression plates made using either 0.5,0.75 or 1mm stainless steel. i used them befor when turboing zetec engines and they worked realy well.

[p fandango]

Would the block need boring out with s60r rods and pistons?
yes, T-5's use 81mm bore. S60R's use 83mm bore

[daza-b]

what bhp are the s60r rods and pistons good for?

[AndysR]

Why go to the trouble of lowering the compression when the cost of rods are quite reasonable and then your really only limited by how big a turbo you fit...

[graemewelch]

Why go to the trouble of lowering the compression when the cost of rods are quite reasonable and then your really only limited by how big a turbo you fit...

i dont know thats why im asking the question. a decomp plate will be £50 so might of been useful. just trying to find out what people want. im willing to put the time to design and develope these items. a lot of which is only available from the states or sweeden but without knolodge and feedback from yous fella i cant do it

[AndysR]

i dont know thats why im asking the question. a decomp plate will be £50 so might of been useful. just trying to find out what people want. im willing to put the time to design and develope these items. a lot of which is only available from the states or sweeden but without knolodge and feedback from yous fella i cant do it

That's fair enough, I like your thinking and realistically if it wasn't for the rods being so readily available then it might be worth it but when you consider that once the rods are replaced with forged ones that the next item to go would be a liner your pretty much clear of most peoples budgets at this point because your talking 450-500 hp plus on the 2.3 at this stage. Also a by product of lowering the compression is loss of throttle response and low down torque you'd have to increase boost higher up to compensate and then by that point you might as well have fitted rods as your going to need to at this point onwards. I suspect by lowering the compression and losing the aforementioned items your probably going to loose some of T5's character in that it won't be the torque flexible engine it's known as...?

[graemewelch]

That's fair enough, I like your thinking and realistically if it wasn't for the rods being so readily available then it might be worth it but when you consider that once the rods are replaced with forged ones that the next item to go would be a liner your pretty much clear of most peoples budgets at this point because your talking 450-500 hp plus on the 2.3 at this stage. Also a by product of lowering the compression is loss of throttle response and low down torque you'd have to increase boost higher up to compensate and then by that point you might as well have fitted rods as your going to need to at this point onwards. I suspect by lowering the compression and losing the aforementioned items your probably going to loose some of T5's character in that it won't be the torque flexible engine it's known as...?


cheers andy. just the sort of answer that im looking for. lots of high quality items are going to hit the forum soon hopfully. im just in process of developing stuff and showing people what im capable of and hopfuly in the new year ill be self employed and giving it 200%

[stribo]

I think the decomp plates are a good idea if you're converting a n/a engine to turbo-charged, but not much point fitting them to an engine that's already turbo-charged.

[Tomcat]

But if you lower the compression ratio then isn't the car going to be down on power when the turbo's now on boost?... ie... it's going to be laggy?

[stribo]

But if you lower the compression ratio then isn't the car going to be down on power when the turbo's now on boost?... ie... it's going to be laggy?

Yeah, I think that's what Andy was saying about losing low down torque.

[graemewelch]

for a turbo car you need lower compression than a n/a engine. with lower compression you can safley run higher boost but as andy say with the lower compression its going to make of bost driving slightly flat. but if yous have any idea speak up.

[Wobbly Dave]

I am lowering the compression with my rebuild (amongst other things). I am looking at 8:1 rather than the standard 8.5:1.

The extra room should in theory allow more Fuel/Air to be pushed in. Off boost performance will be compromised.

[stribo]

Not an idea, but I remember about 10 years ago Saab were trying to develop a variable compression engine, don't know what happened to the research.

[graemewelch]

i must be cracking up. just got this mad idea in my head, wonder what a tubular alloy subframe would be like. would certainly reduce a lot of wieght.

[Wobbly Dave]

Subframe is already hollow so it would depend what you planned to make it out of. I can weigh the OEM subframe if you like?

[graemewelch]

aye if dont mind. my heads full of mad ideas. just love the chalange of making high quality items that are great mods

[claymore]

I am lowering the compression with my rebuild (amongst other things). I am looking at 8:1 rather than the standard 8.5:1.

The extra room should in theory allow more Fuel/Air to be pushed in. Off boost performance will be compromised.
What sort of boost are you expecting to run Dave?

[Wobbly Dave]

I have no target particularly - just to tune it the best I can. Hell it might not even work.

[charlie-r]

Lowering the compression is only really useful if you crank the boost right up, and have the ECU properly tuned with correct ignition timing for the type of fuel you're using e.t.c. if you get that right you can add mad power safely. With a decent ignition tune you won't see a drop in low end torque. Give it a bash, the boost capabilities wi be crazy if you get it right.

[Wobbly Dave]

the GTX I have is more than capable of running the full spectrum.

[claymore]

I can boost to 30psi with the compression ratio I have now, how much boost do you want Dave....lol

[Wobbly Dave]

Enough to beat Dean.

[claymore]

Enough to beat Dean.
If you intend to beat Dean, you had better do it next year, because none of you will have a hope in hell in 2015

[Wobbly Dave]

Why is pedro coming back LOL. Just kidding.

Dean is the current target. I need to find about a second to really make a mark.

[Nealevo]

I need to find about a second to really make a mark.

You could just learn how to drive correctly..... Just a joke :)

[Wobbly Dave]

You could just learn how to drive correctly..... Just a joke :)

you offering lessons?