different compression ratio's

[MeisterR]

not looking for a lot of power ??? it is quite a big turbo for a tiny 1.3 litre.
I don't think you'll see 1 bar boost before 4500 rpm
what would you mean when you say "lot of power" ???

The GT2860R have a few different trim, and I think the -10 (smallest one) is similar to the HKS GT-SS turbo and they are relatively responsive for its size.

The -10 is a 300bhp turbo (or around there), so you can realistically expect around 250 - 280 bhp out of them depending on how hard you want to boost it.

 

[MeisterR]

on a budget = 4e td04. but thats completely off topic.

this thread is about compression or the need for higher comp to save on lag, and the thread starters interest was in getting a td04 that wont drop off boost between gears, the simple answer is it wont and if it does somethings wrong.

Phil

Well, that pretty much sums it up.

Also, another thing worth noting is that high compression also make the car drive better "off boost".
The long as the map is good and safe, it will make an overall better car to drive, but you can't run as much boost as a low compression engine.

 

[azerty]

The GT2860R have a few different trim, and I think the -10 (smallest one) is similar to the HKS GT-SS turbo and they are relatively responsive for its size.

The -10 is a 300bhp turbo (or around there), so you can realistically expect around 250 - 280 bhp out of them depending on how hard you want to boost it.

I never said it wasn't the case
i was refering to what you said here :

Have anyone play with ball-bearing turbo such as GT2860R, they might do pretty well if you are not looking for a lot of power.

so you mean 300 hp is not lot of power on a 4e then ?
or I have misunderstood something ?

 

[GP82]

Reducing the deck height with a .6mm headgasket + skimming head & block will raise the comp ratio and make a more responsive engine, simply because now you have more compression in the cylinder = more energy for the crank = more heat generated @ rings and pistons. Some builders have said reducing the deck height = less chance of gasket failure? You also got to keep in mind if you plan to run high boost, the piston rings have to be able to take that extra heat generated from the higher comp ratio because you have now reduced the deck height or the squish band inside the engine; distance between the piston @ tdc and closed valve.

Why did Toyota build such a low comp ratio engine for a little CT9 even thou they have access to good fuel, i think it was for reliability and to last a long time with minimum stress on rings and pistons.

 

[GP82]

but the problem is not the pistons but the rods ..rods are weaker than the 5EFHE rods and especialy when it is on high compression...

Yup, the higher comp engine will also effect the rods directly. The higher energy output from a forced high comp engine + spark advance will do damage eventually, energy going from the piston, piston pin, rod! You are asking the rods to do near three times the work depending on how high your comp ratio is.

 

[MeisterR]

so you mean 300 hp is not lot of power on a 4e then ?
or I have misunderstood something ?

I was thinking it will make around mid 200's bhp with a -10 and sensible boost level, so that would be similar to the TD04 power with presumably more responsiveness.

I guess I should of been a bit more specific when I name the turbo because it does have quite a "large" range to choose from.

 

[Phil]

are you still talking about a gt2860? or is the 10 a smaller exhaust side?

td04 isnt big like.

Phil

 

[MeisterR]

are you still talking about a gt2860? or is the 10 a smaller exhaust side?

td04 isnt big like.

Phil

As far as I know, it is a different trim on the compressor wheel, not 100% positive as I skip the twin turbo when went straight for a big single. :haha:

Actually, this went a bit off topic now from the high comp question...
But it looks like someone been asking about a GT28R and it also seems like someone had use it on a 4E engine already, so lets carry the discussion further on the more relevant tread if we are to continue.

Oh, while we are still on the topic of compression ratio.
One thing I did on my engine was to take out ALL the squish pad and polish to combustion chamber in the head along with some port matching.
This lower the static compression for running high boost, and we kind of done this as an "test" to see if it works well.

My mapper actually prefer that as he said squish pad on high boost engine sometime do weird thing... where it is more "predictable" if it doesn't have any squish pad. (I am not 100% what he meant, but that was "about" what he said I think.)
I know it is against the norm but the combo works well... I am running 2.0 bar spike dropping down to 1.8 bar at redline just incase you want to know.