Turning up the boost on 93 & Alky?

[Turbo Negro]

I'd like to turn my boost up from 20 to as close to 30psi as possible & maintain zero knock on 93 & Alky. From what I've read so far, I realize that I may not be able to get there without wiring the wastegate closed. I don't necessarily want to go that route, so I'll see how far I can go with a new HD actuator first. Also my chip was setup for a max of 25lbs, and I don't know if this will affect my efforts either. Is this the point where the wg solenoid will kick in? If so, I'll leave it as is for now.

I plan to log a handful of runs & bring the boost up slowly, say in 1-2lb increments, unless there is another recommended method. Are there any other changes required to do so, or do I just need to increase the alky as I go to curb any detonation? Any pointers on the Alky Control settings (initial & gain) from anyone who's already done it with a stock 109 & turbo?

Also anyone have any idea of what I plan to gain by doing this? I think I read around 10hp, .10sec ET, or 1mph for each additional psi. Is this accurate? If so, I may be able to get a mid 12 quarter mile at around 107mph with 25lbs boost. Sound right to you guys?

 

[c n avoid87]

What size turbo are u working with?

 

[Turbo Negro]

Stock turbo

 

[SS502]

I'd like to turn my boost up from 20 to as close to 30psi as possible & maintain zero knock on 93 & Alky. From what I've read so far, I realize that I may not be able to get there without wiring the wastegate closed. I don't necessarily want to go that route, so I'll see how far I can go with a new HD actuator first. Also my chip was setup for a max of 25lbs, and I don't know if this will affect my efforts either. Is this the point where the wg solenoid will kick in? If so, I'll leave it as is for now.

I plan to log a handful of runs & bring the boost up slowly, say in 1-2lb increments, unless there is another recommended method. Are there any other changes required to do so, or do I just need to increase the alky as I go to curb any detonation? Any pointers on the Alky Control settings (initial & gain) from anyone who's already done it with a stock 109 & turbo?

Also anyone have any idea of what I plan to gain by doing this? I think I read around 10hp, .10sec ET, or 1mph for each additional psi. Is this accurate? If so, I may be able to get a mid 12 quarter mile at around 107mph with 25lbs boost. Sound right to you guys?

Not saying you can't do it, but your sig. has stock turbo & IC... you got some good upgrades, why try and max out and blow your heads/motor? Can get there faster and cheaper in the long run with an upgrade to the turbo , IC, and converter. Just my opinion.

 

[theCATman]

Stock turbo & 30 PSI? Are you NUTS?!?!

The stock turbo is blowing such hot air by 20 PSI you could bake a ham in the airstream. Not to mention anything over 20 PSI is wayyy over its effiency range.

If you want to push it, get a bigger turbo that has an effiency range in the 25-30 range. And as said before, a bigger I/C & looser converter to match.

Or, just be happy where you are with a solid low/ mid-12s car.

 

[KEVINS]

The stock turbo is not capable of producing that much boost (too small) unless you completely plug your tailpipes off so all the exhaust is backed up in the intake manifold..

The most you will ever get out of the stock turbo on a free flowing system is 23-24 psi and that is if you completely close off the wastegate. If you get more than 24psi then your exhaust system is restricting flow. You might be able to spike to 25psi+ in first gear but the boost will fall back down.

Been there done that... That's why I stepped up to the new turbo in my sig.

ks

 

[Turbo Negro]

I don't want to blow it up, and that's why I asked here for advise first. Tune is everything regarding performance & longevity. I'd like to accomplish a safe balance. That's why I went the methanol injection route to begin with. I'm not looking to change the engine's max RPM, just it's effeciency for a given RPM. If the Alky is enough to keep it from detonating, by providing both octane & cooling why not use it to it's potential?

I'm getting a new trans & converter soon because I already found the weak link with what I've currently got. I want the car to be solid before adding any more power and plan to have both installed before turning it up. I've also got a new turbo in the works, but wanted to try to max the stocker first.

Just wondering how far, with regard to tune, I can go before upgrading. Sounds like about 23-24lbs boost.

Any tips on how to do it using Alky Control? Any other changes required?

 

[TT/Ameasap]

I ran a stock turbo to 30psi on alkycontrol kit in 2003 or 4. I was gunning for fast Eddie Brewer. Well.... it just doesnt have extra power beyond roughly 25psi. I ran alky on 11 to compensate and there was no steam left. Stock block,heads,turbo. Low 12's high 11's is what it felt like and I did a lot of racing back then. That car was 11.4 11.5 all day long with a best of 11.3 on a Ta49.
Upgrade turbo and you will be surprised how much more muscle you gain.

 

[earlbrown]

Never aim for a specific boost #. That's practically bench racing with a pressure gauge.

Set up your alky and add boost 1/2 to 1 pound at a time. Turn for zero knock and the next thing you know you're hauling ass. And hauling ass is way better than a gauge that reads 5#s or 40#s.

 

[Bescurred]

Stock turbo is done at 22psi...I wouldn't go any higher than that.

fwiw I went 12.20's on the stock turbo with bascially the same stuff you are working with minus the control arms and MAF stuff. You should be able to go 12.0's with a really really good 60ft.

 

[bison]

The stock turbo won't make more than 24-25psi and it will drop boost as rpm gets over 4500rpm. It won't blow your engine or do any other damage as long as it's not detonating either. I did it for a couple years back in the 90's. I went 11.88 on the stock turbo this way. Others have gone quite a bit faster. Better air and traction would increase the potential. The stock turbo has been 11.30's.

 

[bison]

The stock turbo is not capable of producing that much boost (too small) unless you completely plug your tailpipes off so all the exhaust is backed up in the intake manifold..

The most you will ever get out of the stock turbo on a free flowing system is 23-24 psi and that is if you completely close off the wastegate. If you get more than 24psi then your exhaust system is restricting flow. You might be able to spike to 25psi+ in first gear but the boost will fall back down.

Been there done that... That's why I stepped up to the new turbo in my sig.

ks

If you restrict the exhaust it will further reduce the boost. Restriction equals lost ex energy. The highest boost you can get is with the wastegate closed and dumping the exhaust immediately off the turbo. The rapid pressure drop as the ex leaves the housing will increase the turbine speed to it's max. In colder air the boost will be higher from the denser air charge and available ex energy

 

[KEVINS]

If you restrict the exhaust it will further reduce the boost.

I agree for the most part but it depends on how much of a restriction. I was getting 26psi off my stock turbo with factory exhaust through all gears and when I told Julio this he said the extra boost was due to back pressure caused by the exhaust. I opened my dump and the boost fell to 23psi. This is what I was "over indicating" in my above post.

ks

 

[TT/Ameasap]

That 11.3 "stock" turbo was massaged.

 

[Mr.Spool]

i ran 30psi on the stock turbo on bone stock motor with a single m15 nozzle,car was a lot of fun.turbo was def out of breath as a 49 upgrade at 25 psi was more powerfull,either way stock combo with a meth kit and a built trans was a fun combo with no drama and a great street combo.

 

[we4Mateo]

The stock turbo won't make more than 24-25psi and it will drop boost as rpm gets over 4500rpm. It won't blow your engine or do any other damage as long as it's not detonating either. I did it for a couple years back in the 90's. I went 11.88 on the stock turbo this way. Others have gone quite a bit faster. Better air and traction would increase the potential. The stock turbo has been 11.30's.

Thank you. My buddy is afraid of high boost numbers too but boost is just a measure of restriction. I couldn't get more than 23psi out of my stocker but I upgraded to my te44 quickly after that. People are amazed I try to make 30psi but the engine would be more likely to blow up at less boost with a bigger turbo. I say run that little guy til it won't go any higher! Btw, the alky system well automatically increase pressure as long as you are using the 3bar map that came with your kit. You'll need to add fuel to your tune but the alky should be left alone until you see knock. You control the afr through the tune though and you'll need more gas unless you run an extender chip or sd chip that adjusts automatically.

 

[bison]

I agree for the most part but it depends on how much of a restriction. I was getting 26psi off my stock turbo with factory exhaust through all gears and when I told Julio this he said the extra boost was due to back pressure caused by the exhaust. I opened my dump and the boost fell to 23psi. This is what I was "over indicating" in my above post.

ks

Without the shaft speed, ex pressure and manifold pressure there's no way to make any accurate conclusions.

 

[Turbo Negro]

Thanks everyone for the replies. Plenty of good info here.

Btw, the alky system well automatically increase pressure as long as you are using the 3bar map that came with your kit. You'll need to add fuel to your tune but the alky should be left alone until you see knock. You control the afr through the tune though and you'll need more gas unless you run an extender chip or sd chip that adjusts automatically.

So, to add fuel to the tune do I increase fuel pressure on the rail using the regulator? Any rule of thumb or calculations to go by?

 

[turbocamino1]

the TT chip you have is programable... you need to get the directions with the fuel and timing charts. I dont see a scanmaster listed but your chip works through it so.. is a must. unless you can tune through a p/loger? You have to know your ohh too's to fine tune system with a 5.7 chip. You'll spend 500 between those two items