Higher Gears for Turbo Cars

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T56MaxTorq

T56MaxTorq

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318 running 13 lbs boost 904 auto 3500 stall. Pulling onto boost at 2500 and max boost by 4000. I have a boost control module for my Megasquirt but havent used it. Anyone have experience with any boost control? Want less tire spin off the line but still have a hard launch. Street not strip.
 
I take it that you’re just running it off the wastegate spring right? What’s the boost control module? MAC valve, dual MAC, bleeder?

Edit to add: Check out this pdf by Holley on boost control. Lots of good info in it, even if you aren't using Holley efi, the concepts should be the same as MegaSquirt.

https://documents.holley.com/199r10628rev2.pdf
 
Don't know anything about boost but I will comment on gears.
When I was racing in the Slant Six class the cars with turbos did have lower numerical gears.
Most were running 2.76-2.94 and running 12 seconds.
 
Darter6 said:
Don't know anything about boost but I will comment on gears.
When I was racing in the Slant Six class the cars with turbos did have lower numerical gears.
Most were running 2.76-2.94 and running 12 seconds.
Click to expand...

I just tried to tell that to the racer guys in that forum!
 
Between the two threads you started yesterday you could get a lot of help if you posted more details on your car(I couldn’t find a build thread). Here in forced induction we need your engine build specs, what turbo, hot side pipe size etc. We can help get you boost sooner or later if that’s what you need. The guys over in the racing forum need info like your tire size and type, suspension setup(front and rear) to help you out. With that they can help get your car to hook, and they’re very knowledgeable in that area.

I do not see a reason to change your rear gears; 3.55’s will work just fine. Spend your money elsewhere.
 
turbovan said:
Between the two threads you started yesterday you could get a lot of help if you posted more details on your car(I couldn’t find a build thread). Here in forced induction we need your engine build specs, what turbo, hot side pipe size etc. We can help get you boost sooner or later if that’s what you need. The guys over in the racing forum need info like your tire size and type, suspension setup(front and rear) to help you out. With that they can help get your car to hook, and they’re very knowledgeable in that area.

I do not see a reason to change your rear gears; 3.55’s will work just fine. Spend your money elsewhere.
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Hey thanks!

As for specs:

Oem bottem end magnum 318. EQ iron heads w/ 1.92 valves. Standard bore, About 8.8:1 c/r. All roller valve train, turbonetics 62-1 turbo, tial 38mm waste-gate .84 a/r. I use e85 with 44lb injectors in a M1 single plane intake. Megasquirt 2 controller, diy missing tooth wheel crank sensor, ford style e coil, left hand alternator, all stainless pipe, 1.5” into 2.5” into turbo out to 3” single exhaust w/ flow thru muffler and short exit. Edelbeock 1000 cfm throttle body w/ IAC. Aeromotive fuel pump and regulator, trunk fuel cell and battery. 904 trans, 3200 stall converter. 3.55 gears and 27” tires.
 
Hook up the boost controller, it'll help create boost earlier (if you need/want it) and you can set up a table to limit boost by mph or rpm or gear. Not taking advantage of the boost control is leaving performance on the table.
 
That small turbo and hot side should spool much quicker. I would be surprised if you couldn’t brake boost to your 13psi max. DNasty is right, a boost controller can bring boost in quicker than running off spring pressure. Also, you could give launch control a try which will build boost quicker.

Is it possible you have an exhaust leak before the turbo?
 
You’ll likely need to launch at full boost and dead hook if you want to stand a chance against an electric car. Some extra boost would definitely help if the tires can hold it.
 
Just to drive the point home, running the wastegate off the spring alone will cause the wastegate to open prior to reaching the rated spring pressure. IE, your 13lb wastegate spring is probably starting to crack the wastegate valve much earlier than that, probably around 7psi. Running a MAC valve boost controller allows you to essentially pin the wastegate valve shut until you reach your requested boost pressure. It does this by pushing up under the wastegate valve diaphragm, either with compressor discharge air or CO2 from a bottle, keeping the valve closed.
 
turbovan said:
That small turbo and hot side should spool much quicker. I would be surprised if you couldn’t brake boost to your 13psi max. DNasty is right, a boost controller can bring boost in quicker than running off spring pressure. Also, you could give launch control a try which will build boost quicker.

Is it possible you have an exhaust leak before the turbo?
Click to expand...

I should mention I’m high altitude and run from 6-10,000 ft., my turbo seems to fall nicely on the map. Altitude correction is negative 3 psi. Running 13 psi up here is like running 10 at sea level. I have to play catch up with less atmospheric pressure. I don’t think I have an exhaust leak.


turbovan said:
You’ll likely need to launch at full boost and dead hook if you want to stand a chance against an electric car. Some extra boost would definitely help if the tires can hold it.
Click to expand...

EVs aren’t too fast, most run 11’s, 12’s and they’re fat.
DNasty777 said:
Just to drive the point home, running the wastegate off the spring alone will cause the wastegate to open prior to reaching the rated spring pressure. IE, your 13lb wastegate spring is probably starting to crack the wastegate valve much earlier than that, probably around 7psi. Running a MAC valve boost controller allows you to essentially pin the wastegate valve shut until you reach your requested boost pressure. It does this by pushing up under the wastegate valve diaphragm, either with compressor discharge air or CO2 from a bottle, keeping the valve closed.
Click to expand...

Man I’m not sure what boost control module I have. It’s a diyautotune for mega squirt. Has 2 air ports.
 
T56MaxTorq said:
I should mention I’m high altitude and run from 6-10,000 ft., my turbo seems to fall nicely on the map. Altitude correction is negative 3 psi. Running 13 psi up here is like running 10 at sea level. I have to play catch up with less atmospheric pressure. I don’t think I have an exhaust leak.




EVs aren’t too fast, most run 11’s, 12’s and they’re fat.


Man I’m not sure what boost control module I have. It’s a diyautotune for mega squirt. Has 2 air ports.
Click to expand...


If it’s this one, this is called a single MAC valve boost controller. If you look at diagram 2 that’s the best way to set it up, assuming you have a dual port wastegate. Have a look through the Holley pdf I posted above, it’s the same setup as megasquirt just the menus look different.
 
T56MaxTorq said:
EVs aren’t too fast, most run 11’s, 12’s and they’re fat.
Click to expand...
Are you racing 1/4 mile on the street? If that’s the case you might as well just turn up the boost and run them down at 130.

Otherwise you’re talking about sticking with a torquey vehicle that launches perfectly every time. So you’re after more boost and traction from a dig?

I didn’t mean that your turbo is too small for your application. Just that I think it should spool sooner; even at altitude. I could simply be wrong, but we’ve listed a couple methods that should help either way.
 
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T56MaxTorq said:
I should mention I’m high altitude and run from 6-10,000 ft., my turbo seems to fall nicely on the map. Altitude correction is negative 3 psi. Running 13 psi up here is like running 10 at sea level. I have to play catch up with less atmospheric pressure. I don’t think I have an exhaust leak.




EVs aren’t too fast, most run 11’s, 12’s and they’re fat
Click to expand...
This is me vs a Tesla Plaid. It was running 6.15 1/8th mile times... I’m not an EV fan but I’d never call them slow
 
I rode in a dual motor sport model of the Tesla and that sumbitch was silly quick. ESPECIALLY given how simple and daily driveresque that car was.

The Plaid supposedly can do 10s. That is a fast damn car. NOW....the plaid has quite the preparation time to do the super fast run bit nonethetit can be done.

If you don't like the prep time then you're stuck with slow poke 11s :rofl:

I'm not an ev fanboy but dang they do accelerate quickly.
 
Mean416 said:
I rode in a dual motor sport model of the Tesla and that sumbitch was silly quick. ESPECIALLY given how simple and daily driveresque that car was.

The Plaid supposedly can do 10s. That is a fast damn car. NOW....the plaid has quite the preparation time to do the super fast run bit nonethetit can be done.
Click to expand...
The Plaid runs bottom 9’s at 150 and dead hooks every time. I don’t think many gassers stand a chance from a dig. I fear the day I watch a Kia walk away from me while I spin :lol:
 
I rode in my friends plaid he rented on Friday and wow! The acceleration was absolutely unreal. I know I’ll never obtain that type of acceleration or 1/4 ET but it’s fun to strive for
 
Hemirunner said:
This is me vs a Tesla Plaid. It was running 6.15 1/8th mile times... I’m not an EV fan but I’d never call them slow
Click to expand...

Man I gotta agree with that. I saw a rookie so raw he couldn't find the starting line, or the finish line, run a 6.45 eighth by accident, in a stock Tesla. (I don't know the model, I don't want to pay that much attention).
 
We ran 10.70's with a 2.76 with a blow thru 360 non intercooled. It slipped the converter pretty good. Went to a 3.23 and some tuning and went 9.90's.
Doug
 
dvw said:
We ran 10.70's with a 2.76 with a blow thru 360 non intercooled. It slipped the converter pretty good. Went to a 3.23 and some tuning and went 9.90's.
Doug
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That’s a huge gain. I’m running 3.73s since it’s a heavy car. It would probably be quicker if I went back to the 4.10s.
 
even the big big turbo power guys on other forums say to gear the car for the 1/4 just like you would a NA combo. No point in crossing the stripe at low rpm and high converter slippage; unless it’s a highway car.
 
dvw said:
We ran 10.70's with a 2.76 with a blow thru 360 non intercooled. It slipped the converter pretty good. Went to a 3.23 and some tuning and went 9.90's.
Doug
Click to expand...
Was that the only change?? Huge gain!
 
Mean416 said:
I rode in a dual motor sport model of the Tesla and that sumbitch was silly quick. ESPECIALLY given how simple and daily driveresque that car was.

The Plaid supposedly can do 10s. That is a fast damn car. NOW....the plaid has quite the preparation time to do the super fast run bit nonethetit can be done.

If you don't like the prep time then you're stuck with slow poke 11s :rofl:

I'm not an ev fanboy but dang they do accelerate quickly.
Click to expand...
Those EV are fast, not a fan but...
Me and my friends do the local flash light drags, always pit in the same spot.

On weekend, a lady in her mid 40's shows up in a Tesla, pitted right beside us.
That thing was quick and consistent.
She was very modest, said she had nothing to do that day, and wanted to try drag racing, brought her kids out and had a blast.
The car is kinda weird, just a steering wheel and a tv set.
 
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