boost and turbo size

[nigelboyne]

lads which puts more strain and pressure on an engine does running the smaller turbo with more boost or the larger turbo at lower boost ie. 61mm gtx3582r at 2 bar or 67mm turbo to4z or 6765precision at 1.5 bar

[Ian C]

It's all to do with cooler air for a given flow rate/pressure. Bigger turbos are more efficient at compressing larger volumes of air, so the air heats up less. The problem with hot air is twofold - one, you get less oxygen density so you lose power, and two, hot intake air can cause detonation - running rich fuel mixes in turbo engines is actually just to cool down the insides of the combustion chamber

 

You can detonate any engine to death with relatively little boost on a small turbo if you try hard enough "Strain and pressure" on the engine sounds more like the result of how much power you're running. Higher revs is the big engine killer, though.

[Wez]

1.5bar, 2.0bar pah, what pressure do you think is in the cylinder under combustion.

[nigelboyne]

1.5bar, 2.0bar pah, what pressure do you think is in the cylinder under combustion.

 

sorry for my ignorance i guess i am asking for reliable 550/600hp is it safer to go for the 67mm size turbo or is 2bar on a 61mm turbo out of its efficency and likely to fail,

[Ian C]

2bar would need some serious octane fuel, and would probably net you more than 550bhp

 

There are a lot of discussions about turbo sizing and selection, also there is Ryan's dyno plot comparision thingy somewhere that gives you an idea of how different turbos behave. A T67 at 1.4bar or thereabouts will net you those power figures though, and it's a very nice match to the 2JZ engine.

[Luxluc]

sorry for my ignorance i guess i am asking for reliable 550/600hp is it safer to go for the 67mm size turbo or is 2bar on a 61mm turbo out of its efficency and likely to fail,

 

For your power goal, I would go for a 67mm ... you'll need to run a 60/61mm at high boost to get close to 600 bhp, unless you go for a set of wild cams. My PHR Stage 1 was pushing around 550 on stock cams at 1.5 bar.

[Nic]

sorry for my ignorance i guess i am asking for reliable 550/600hp is it safer to go for the 67mm size turbo or is 2bar on a 61mm turbo out of its efficency and likely to fail,

 

A 61mm turbo + cams and all other supporting mods should make around 550hp at 1.4bar

 

A 67mm turbo + cams and all other supporting mods should make around 600hp at 1.4bar

 

The smaller turbo will give you faster spooling, the larger turbo more top end power.

[Ricky49]

Surely wouldn't a 61mm at 2bar be out it's effiency range.

[Luxluc]

Surely wouldn't a 61mm at 2bar be out it's effiency range.

 

SteveL had his PHR Stage 1 running to its absolute max .. which was around 580 (with cams and head).

[nigelboyne]

so 580 is a good way shy of 770hp that garret claim from there new gtx35r

[Luxluc]

so 580 is a good way shy of 770hp that garret claim from there new gtx35r

 

Pay attention Nigel ... some power figures claimed by the manufacturer may only be achieved on race gas.

Edited November 24, 2010 by Luxluc (see edit history)

[Nic]

so 580 is a good way shy of 770hp that garret claim from there new gtx35r

 

That'll only be achievable on a bigger displacement engine.

 

From the Garrett website

 

Horsepower 450hp - 750hp

Displacement 2.0L - 4.5L

Edited November 24, 2010 by Nic (see edit history)

[Bailey.]

I'm so tempted to change my t88 before I even fit it with all this talk!!!

[Ian C]

I'm so tempted to change my t88 before I even fit it with all this talk!!!

 

I would, to be honest - the T88 is very old skool and laggy. Even the T67DBB has serious competition with the GT35R and the new Borg Warner stuff, according to the results I've been hearing on here.

[Bailey.]

What kind of spool will a 6765 billet journal bearing have?? It just seems such a waste! Tbh it's not lag that bothers me, I'm not going to be dipping in and out of boost on wot When changing gear so no issue! But I am concerned at making more power than I am going to be able to use,a t88 with 264 cams. No idea what it will make really, hopefully high 500s! Only a couple of weeks till I get started now!

Edited November 24, 2010 by Bailey. (see edit history)

[Ian C]

I've got no idea - swapping the turbo over won't be that hard once it's all in place, but you probably won't go backwards by getting a more modern one. Flog the T88 to an MR2 or RX7 owner on ebay, they seem to love them.

[Bailey.]

I've got no idea - swapping the turbo over won't be that hard once it's all in place, but you probably won't go backwards by getting a more modern one. Flog the T88 to an MR2 or RX7 owner on ebay, they seem to love them.

 

For a start what's it worth, and what am I really going to gain around 400rpm realistically?!! As you said, no great shakes to change at a later date tbh!

[Ian C]

For a start what's it worth, and what am I really going to gain around 400rpm realistically?!! As you said, no great shakes to change at a later date tbh!

 

I don't know the answers to these questions, sorry You could gain 1000rpm of better power band. Going from a T67 journal to a T67 DBB was an immense difference in driveability, even though the numbers were around the 500pm mark for spool improvement. The T67 journal tapdanced all over a T88 even back then, as well.

[Bailey.]

I don't know the answers to these questions, sorry You could gain 1000rpm of better power band. Going from a T67 journal to a T67 DBB was an immense difference in driveability, even though the numbers were around the 500pm mark for spool improvement. The T67 journal tapdanced all over a T88 even back then, as well.

 

By topdanced you mean spooled quicker??

[Chris Wilson]

http://www.turbobygarrett.com/turbobygarrett/tech_center/tech_center.html

 

Read through Basic, Advanced and Expert sections, it's a pretty good resource by a world leading company.

[dandan]

Geo has a journal 6765 i think

[davej705]

http://www.turbobygarrett.com/turbobygarrett/tech_center/tech_center.html

 

Read through Basic, Advanced and Expert sections, it's a pretty good resource by a world leading company.

 

Really good read that

[Ricky49]

I have 6765 journal been fitted to my single conversion and LeeP was saying I should see full boost just before 4k.

[JamieP]

For a start what's it worth, and what am I really going to gain around 400rpm realistically?!! As you said, no great shakes to change at a later date tbh!

 

A lot worse than that, T88 won't see much in the way of positive boost in first gear.

[Bailey.]

Yeah I remember you saying about first gear Jamie! Think we will just have to see how I get on with, seems silly not to give it a go! What power did yours make Jamie?