Accelerated Performance 2013 BRZ - FRS Turbo Kit Designing

[serialk11r]

Originally Posted by Coheed

That's what everyone said about the 11.5:1 compression 2zz motor in the Celica. Yet there were a lot of people who turbo'd them. They made great power too.

10 years ago, if Toyota said they were bringing a 12.5:1 compression engine to market, people would say "Impossible! It won't work on 91 octane!"

13:1 is out of the question... right? Then the Prius was released. Overseas, they get 14:1 with 93 octane. Blasphemy!

Then mazda pushed 16psi boost through an engine at 9.5:1 compression in the MZD. People realized over 20psi from stock turbo with tuning, all on 91 octane.

I don't think 8psi is out of the question here.

To be completely accurate, the Prius does not have true 13:1 compression because it's rev limited to 4000rpm and set up for very low volumetric efficiency, the actual peak cylinder pressures it sees probably correspond to a 10:1 compression ratio or so. (on a side note, to have a true 13:1 compression the apparent compression ratio would be like 17:1, which might work on 93 gas because there is so little residual exhaust left, but I wouldn't know...efficiency would be through the roof though)

That said, yes Mazda has a 14:1 compression "normal VE" engine that runs on 91 (not even 93!), and yes turbo motors have been doing okay on very high boost for a while. For an NA example though, there was a TRD 3S-GE package that had big cams, 13.1:1 compression ratio, ITBs and exhaust, making like 280hp on presumably 93, from well over 10 years ago :O Anyways, it's all in the tuning as you say.

[bakerr6]

Originally Posted by Calum

I'll take that bet. If I win I get what ever turbo kit you do release for free. If I loose I pay zero dollars for the kit. :happy0180:

Don I don't see any reason to why you shouldn't be able to, barring we can remove the issue with tuning vs. the direct injection. I've seen motors that are 13:1 and 14:1 running 8-10 lbs. of boost, with no issues.

Are you planning on running meth also?

[uspspro]

Toyota hybrids are also atkinson cycle... so it's not apples-to-apples

[Calum]

Originally Posted by bakerr6

Don I don't see any reason to why you shouldn't be able to, barring we can remove the issue with tuning vs. the direct injection. I've seen motors that are 13:1 and 14:1 running 8-10 lbs. of boost, with no issues.

Are you planning on running meth also?

??? Why did you quote me?

[GirlyScions]

Originally Posted by Don@Accelerated

Who wants to bet me I can't make 300hp on the factory compression w/ zero issues?
Any Takers?

Im a bit skeptical. Subaru lowered the compression and the rpms 6k or so on their turbo fa20. And its not even making 300hp. Alot could go wrong with 100 FI hp.

Ill bet. Nothing more than my dignity. But to clarify, "zero issues" = 5 years

[Sportsguy83]

^ Preeeety safe bet

[serialk11r]

Originally Posted by GirlyScions

Im a bit skeptical. Subaru lowered the compression and the rpms 6k or so on their turbo fa20. And its not even making 300hp. Alot could go wrong with 100 FI hp.

Ill bet. Nothing more than my dignity. But to clarify, "zero issues" = 5 years

But peak power comes 1000rpm earlier. Cut the boost, raise the power peak (at the cost of more lag).

[Dimman]

Is the 300 hp bet for whp or crank? Also is it with or without meth injection?

If we're talking 260-270 whp (~300 crank) with meth, I could see that.

300 whp, no meth, I don't think so.

[GirlyScions]

Originally Posted by serialk11r

But peak power comes 1000rpm earlier. Cut the boost, raise the power peak (at the cost of more lag).

Low reving boosted engines are safer than high reving boost engines.

Just think how much power subaru's turbod fa20 would make at 7.5k!

[jedibow]

Originally Posted by GirlyScions

Low reving boosted engines are safer than high reving boost engines.

Just think how much power subaru's turbod fa20 would make at 7.5k!

What you need to consider if you are building a motor that revs at a high level is Rod to stroke ratio (foced induction does not play into it), because as you increase piston speeds the side load on the rotating assembly increases.

This increase in side load is the same whether the engine is seeing boost or not, if the engine is completely devoid of both pre-ignition, and detonation (both of which are the only events that can increase side load when using FI) than the addition of boost (or pressure) in the cylinder will not increase side load. The additional pressure will act perpendicular to the rotating assembly at this point, and only increase cylinder pressure, or the pressure on the piston face. I would also like to point out that the pressures (8-10psi) that the turbo, or supercharger add to the cylinder fail in comparison the the pressures the cylinder has to endure once combustion takes place.

If what you say is true, than we wouldn't have any 13b turbo motors reving past 10k, RB26 motors reving past 9.5k, 4g63 motors reving past 9k(I currently have one running 26psi), b16 motors reving past 10k, b18 motors reving past 9.5k.....

I hope my point is made.

G

[rusty959]

Originally Posted by Dimman

Is the 300 hp bet for whp or crank? Also is it with or without meth injection?

If we're talking 260-270 whp (~300 crank) with meth, I could see that.

300 whp, no meth, I don't think so.

Yea thats about what Ive been thinking. Even if I was only a bit over 250 Im still planning on adding meth just for a bit of safety factor. Realistically, im halfway expecting the transmission to go before the engine.

[GirlyScions]

Originally Posted by jedibow

What you need to consider if you are building a motor that revs at a high level is Rod to stroke ratio (foced induction does not play into it), because as you increase piston speeds the side load on the rotating assembly increases.

This increase in side load is the same whether the engine is seeing boost or not, if the engine is completely devoid of both pre-ignition, and detonation (both of which are the only events that can increase side load when using FI) than the addition of boost (or pressure) in the cylinder will not increase side load. The additional pressure will act perpendicular to the rotating assembly at this point, and only increase cylinder pressure, or the pressure on the piston face. I would also like to point out that the pressures (8-10psi) that the turbo, or supercharger add to the cylinder fail in comparison the the pressures the cylinder has to endure once combustion takes place.

If what you say is true, than we wouldn't have any 13b turbo motors reving past 10k, RB26 motors reving past 9.5k, 4g63 motors reving past 9k(I currently have one running 26psi), b16 motors reving past 10k, b18 motors reving past 9.5k.....

I hope my point is made.

G

My bad, kinda vague. Is there not less chance of snapping a rod at a lower rev than when near redline given the same engine with the same boost level?

13b's should also never be used as a comparison to a piston engine either.

[Dimman]

Originally Posted by GirlyScions

My bad, kinda vague. Is there not less chance of snapping a rod at a lower rev than when near redline given the same engine with the same boost level?

13b's should also never be used as a comparison to a piston engine either.

Acceleration forces on rods get much worse as rpm increase. High rpm is harder on a motor than boost.

[jedibow]

Originally Posted by GirlyScions

My bad, kinda vague. Is there not less chance of snapping a rod at a lower rev than when near redline given the same engine with the same boost level?

13b's should also never be used as a comparison to a piston engine either.

Your simple statement was boost and high RPM don't mix, in that case I could sight any internal combustion engine that uses forced induction

Thanks Dimman you always have a way to elequantly state the point I'm trying to make. HaHa