GTQ70 BB+ Methanol+pump..what boost??

[Wazvette]

Greetings everyone..

I currently have a built 231 , aluminum heads , and a gtq 70 BB going into the GN. The car will have a front intercooler, a bigger plenum, and a biger throttle body. A Razor is already in there.My plan is to run it with methanol and pump gas. The question is...what do you think would be a good boost level for that set up. Someone will ask me for my goals. Well...the car will be daily driven but I want it to be set on kill with alcohol (well..as much as i could).

I noticed that a number of people here shy away from more boost on alcohol. just to compare I have Mitsubishi evo that is currently running 32lbs of boost on alcohol and 93 pump. For many years people thought that 21-24lbs is the most that you can do with alcohol and pump on that car. But people discovered later that this was an imaginary threshold and they started dialing more boost ( with more efficient turbos and heads) .

I know its all about timing here. I also know that different platforms work differently and you guys could be achieving better numbers with less boost and more timing. and thats why I am asking :biggrin: what do you think? it would be nice to spin that turbo more.

I am a novice to GNs so please help..


thanks in advance

 

[bison]

What compression ratio and cam? Keep in mind your dealing with 25 year old tech on the Buick. The Mitsubishi has much more efficient heads than the Buick. Dont be decieved by the boost number. If your wanting to maximize the boost you can run reliably then id look at the valvetrain and run a larger cam. More rpm means more hp. You will achieve the same mass flow just at a higher rpm. Ive hit 30 psi a few times long ago with alky on a 9.0:1 iron headed Buick. It took a lot of alky. Not sure the exact amount but it was at least as much as a Razor dual with the pump speed all the way up. I would rather see you rev it more and keep the boost down in the 25 psi range. It will still take a bunch of methanol to keep he detonation away. I am assuming that you have good strong bottom end. The 70GTQ is enough to run mid 130's at 25 psi and the TSM guys ar egoing over 140mph at low boost levels with it. Comp ratio, cam, and timing will be the determining factor on the safe boost level. No sense in being on the edge. If you have a stock bottom i wouldnt run a GTQ. You wont be able to maximize it without breaking the bottom end. The one in my sig is on the edge with zero detonation. It doesnt have a lot of life at 24+psi. No detonation tolerance at all.

 

[fastdon3]

what kind of parts do you have in the motor

 

[The Darkside]

As you can see in my sig below I'm running a stock 109 block that's has RJC's girdle, the 70gtq bb turbo & Razors single nozzle achy kit. I've turned the boost up to 24-25 lbs & got no knock. The achy knob was turned almost completely up, so I'm thinking it's time to add another nozzle before turning it up any further...

 

[Wazvette]

thank you guys for the responces..

its a TSM block..

Eagle forged crank and rods
CP pistions
Girdled and steel center caps
GN1 roller rockers
Double roller timing chain
Max ported GN-1 heads.
Copper head gaskets
Port matched stock intake
BHJ balancer
SFI flexplate

got it from d90Dan ..a great genuine guy

the cams I think will be 218

 

[3.8vsix]

As you can see in my sig below I'm running a stock 109 block that's has RJC's girdle, the 70gtq bb turbo & Razors single nozzle achy kit. I've turned the boost up to 24-25 lbs & got no knock. The achy knob was turned almost completely up, so I'm thinking it's time to add another nozzle before turning it up any further...

What kind of times are you running?

 

[bison]

thank you guys for the responces..

its a TSM block..

Eagle forged crank and rods
CP pistions
Girdled and steel center caps
GN1 roller rockers
Double roller timing chain
Max ported GN-1 heads.
Copper head gaskets
Port matched stock intake
BHJ balancer
SFI flexplate

got it from d90Dan ..a great genuine guy

the cams I think will be 218

You have enough bottom to go with a larger cam. Id go solid if you want to really make a lot of power but your building a daily driver. Regardless i wouldnt go smaller than 224/224 with the race ported heads. Id go for 1.75 rockers too. Need the lift to take advantage of all that porting. What torque converter are you going to run? Compression ratio? Id go with a 17 blade 3600 PTC 9.5 if you have 9.0:1. A little more if less. With the larger cam you can make a lot more hp at lower boost. You want to make power to 6300 with those parts. The 218 will work but will require a little more boost at lower rpms to make the power. Im building a 233ci stock block right now. RPE in CT is doing the machine work. ATR rods and steel crank with JE's. Ill be using a 224/224 hydraulic with 885 lifters and the same heads but matching GN1 intake. 9.2:1. I plan on running 10.0 at 20-22 psi repeateadly. Should go 9.70's if i have enough fuel and torture it. 9.50's if its 4 bolted and i really torture it. The double pumper wont cut it though. Unless i throw a lot of alky at it. That will be my primary driven TR. The S2 will be a little more aggressive with a small solid roller and 4 bolted for sure.

 

[Wazvette]

compression is 9.2:1....i guess i cant push boost much...I was not aware it was that high. Converter will be a 3500.. Brand not decided but maybe PTC.

 

[TT/Ameasap]

compression is 9.2:1....i guess i cant push boost much...I was not aware it was that high. Converter will be a 3500.. Brand not decided but maybe PTC.

You caould swap to thicker head gaskets and run lower compression, but I have been reading up and seeing that a little higher CR on some of the faster cars are doing fine.

Bison,
Is that 224 cam roller?

 

[bison]

You caould swap to thicker head gaskets and run lower compression, but I have been reading up and seeing that a little higher CR on some of the faster cars are doing fine.

Bison,
Is that 224 cam roller?

Billet roller with 885's.

 

[GNVYUS 1]

First the GN crowd kicked off the Methanol craze and we sure weren't running the regular pump gas boost settings when injecting alcohol. Most of us run more boost with our Meth FWIW and a member here has be high 9's on pump and Meth on a 67 turbo.

You got a good setup there, I assume you're tuning with something so you're going to find that threshold of psi and knock really fast if you try to run a set psi # first.

Start low like 18psi and low 20 degrees of timing and keep dialing it in. It won't take long before you're 20+psi with 20 something timing on 93 and Meth.

 

[bison]

compression is 9.2:1....i guess i cant push boost much...I was not aware it was that high. Converter will be a 3500.. Brand not decided but maybe PTC.

You want to run a larger cam on that build or you will have detonation at fairly low levels. You say you want to run 25 psi. Its going to be tight. You will have to throw a lot of alky at it. Keep in mind its a TSM type build with 9.2:1. TSM runs q16 not alky. It has a higher detonation limit than alky and 93 octane for sure. Most run a larger solid cam than i mentioned also. There is a reason for this. They run the higher CR and larger cam because they build the engine to rev higher and make more hp. Think about the mph they achieve on a 29" tire and most have 3.42 gears. 6400+ . The solid cammed guys go even higher as they cross the line. Bmep will get really high with a small cam in that type of engine which will cause detonation. You could play with cam timing but that is more of a bandaid and will give up a lot down low or up high vs the correct larger cam. Just be careful. No detonation is ok at that power level. A 17 blade PTC should get it done with great results. Contact Dusty Bradford

 

[The Darkside]

What kind of times are you running?

I haven't been to the track yet because I've still got a HR rear sway bar I bought several months ago to install & a few other misc items to take care of first...

 

[scot w.]

I ran 27psi boost on the street with Alky & 93 pump gas with my old GN. It also had the 70-GTQ .85 housing, TSM set up and it was killer!!
Here is a short list of what I had:

234cu 109 block
J&E pistons
M&A stageIII Aluminum heads
Match ported intake
221/218 @.050 525 lift cam
1.65 roller rockers
70mm throttle body
70mm plenum
85lb injectors
Razors dual nozzle alky kit ( didn't really need it) The higher the alky knob the better the pump & spray work!!!
PTE stock location I/C
ATR headers
TOO MUCH MORE TO LIST.....

27lbs you will be fine and you'll NEVER get beat on the street!!!!! :biggrin:

Scot W.