Ford Mustang Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter #1
Guys I need an opinion on what turbo size you think I should look into. I am piecing my turbo parts for my first build and I am looking to make 10 second quarter mile times. I am running a stock 302 block with stock internals that came with TRW pistons, GT40X aluminum heads (64cc), TFS 1 camshaft, 1.6 pedestal rockers, GT40 intake(Im swapping to a Holley Systemax with a Phenolic Spacer), Tremec 3550, 3.73 gears(Im switching to 3.27s for better turbo load). I do plan on running 93 pump gas with Alkycontrols 100% methanol kit, 60lb injectors with an Aeromotive 340 pump. I am looking to run a Ceramic Ball Bearing turbo because it spools up faster then a Journal. Please let me know what turbo size you guys would recommend.
 

·
Registered
Joined
·
1,541 Posts
I'm guessing that given your direction you're going to blow off my contrarian advice. Nevertheless, I'm going to give it, so buckle in. If you listen, you'll save yourself a boat load of money that you can invest in other parts of the car or in replacing future broken parts without costing yourself an ounce of power or fun.

Don't swap the gears, man. That "turbos need load" thing is garbage. They do. I'm not debating that. It's just that if you're not blowing off the tires, you're loading the turbos. They'll get the load if you get the traction. Also, there are ways to load a turbo before the launch. With the shorter gear, you're going to come out of the hole harder, which is where it counts the most in a straight line. Your launch will be harder and your ETs will suffer by going to 3.27s. So, leave them in for now. You can always do it later, and when you see they work just fine, you won't bother. You won't need to swap, unless you're doing it for other reasons. So, save your money.

For a stock block H/C/I 302, anything from a 60 to a 70mm T4 flange turbo will spool well on the street for a 302 and provide more than the 500 rwhp that is capable of cracking a stock block. Don't spend more than you need to on the neatest whiz-bang bearings. I did, and it's wasted money, IMO. As long as the turbo isn't oversized, it'll spool very quickly. An old journal bearing Master Power T70 turbo with a .68 A/R turbine housing will spool damn near instantaneously and will boost threshold well under 3k rpm. Back then they went for $500 new. You can find one or something near it in spec for a couple hundred bucks.

The alky is overkill, too, as you'll be able to get to block splitting power on pump gas with a safe, conservative tune. And, the swap to the holley is also unnecessary. It's a fantastic intake, but it's not going to make more low end torque than your GT40, and low end torque is what gets the turbo spun up in the first place. You're also not going to make more power, because once you hit 500 rwhp, that's it, and your block is done. Unless you're willing to frequently replace shortblocks or you upgrade to an aftermarket block, you'll gain nothing from this swap.

Here's the thing, your combo makes ~270-ish rwhp as it sits, n/a. Add 15 psi to that, which with an intercooler you can do on pump gas given your low compression ratio, and you'll be pushing roughly double that at ~540rwhp. That's more than you're going to want to with a stock block. So really, at +/- 13 psi, you'll reach the block's limit.

I'm not going to advise against 60 lbs injectors, because they can and will work, but 42 lbs/hr or bigger will do, and if you plan to control them with the stock EEC-IV, it'll be easier to keep smaller injectors lean at idle and cruise. Good choice on the fuel pump. It'll be plenty.

There, I just saved you gears, intake, fancy bearings, & alky system money, time, and unnecessary complexity! Getting a turbo 302 going is complex and expensive enough.

I would caution you against over revving and over torquing the motor. You can tune out a lower end torque spike when the boost hits by pulling timing. I'd shoot to limit the motor at 550 rwtq, 500 rwhp, and 6k RPM. Maybe set the limiter there and shift at 5800. Tell your tuner to stay very conservative. With 2 psi (~50-60 rwhp) to spare, there's no reason to push it.
 

·
Registered
Joined
·
1,541 Posts
Also, most folks these days go for the On3 crap. If I were in your position, I'd spend the ~$2k and pick up a quality turbo kit from Hellion, B&G, HPP, or have a well-known fabricator with turbo experience make you a custom one. Here's an example, though it's already sold:

https://forums.corral.net/forums/power-adders/2490570-hp-turbo-kit-fox-body.html

The absolute most important thing to get right is the W/G and its plumbing. Don't trust cheap Chinese crap. Tial has always been my go to, but there are other quality brands I'd also run.
 

·
Registered
Joined
·
2,274 Posts
I would keep it at 10psi and beat the crap out of it. 3.27 is good on the street because you will shred the tires 1st-3rd easily. It will be worse with 373's.

What are you tuning with?
 

·
Registered
Joined
·
698 Posts
I will disagree with the previous comment on gears.. I believe 3.27 is a better choice but everyone has their preference. Regardless, its not going to hurt to take it down the track with current gears and see what it does. I would say a 67-70mm would probably be best for street driven fun, with a manual, and give you low lag after shifts. I have a 76 on a 331 with a T5 behind it and Im going down to a BB 67mm with a 96 ar hot side looking for instant spool thats not restrictive up top. I would go with 80s as they are almost the same price as 60s and you could easily go to e85 and have the head room (assuming you have a 340lph). Why buy injectors twice? Unless you go with a dart block, its doubtful youll ever outgrow 80s. Get them at PowerAdderSolutions if you do. There are so many companies selling fakes. I know they sell genuine. Fakes are impossible to tune. I personally dont like methanol/alcohol injection but again, everyone has their preference. In my opinion E85 is a better choice and you dont have to worry about forgetting to fill the tank and having those issues. Maybe you live somewhere you cant get it but if you can there are always options for dual tunes as well if you need long distance driving.
 

·
Registered
Joined
·
1,541 Posts
Dwain, with your 80s, what do your AFRs look like at idle and cruise? Is the Moates QH still an EEC-IV based tuner? It was when I looked at it, if I recall correctly.

I run 120s without issue, and I self-tune like you, but I'm running a stand-alone with awesome injector drivers (BS3). I was under the impression that the EEC-IV could not actuate the injectors quickly enough to keep AFRs at idle and very low loads reasonable. What has your experience on gasoline been?

In any case, if the structural limits of the short block are the issue, and you can reach those limits on pump gas, and pump gas is still cheaper, more mileage/$ efficient, and more prevalent anywhere in the country, why run E85? This is coming from a guy whose car made 954 rwhp on E85. So, I'm well aware of its benefits.

Regarding gears, the optimal gear will depend on your final power output. A 3.73 gear on a 26" slick, keeping in mind that it will grow an extra inch or so by the end of the track, would be capable of ~130 mph at 6000 rpm. Dependent on race weight, driver, and other variables, I'd expect a Fox to go ~130 mph, or perhaps a little under, at 500 rwhp. That is damn near perfect! Now, if he were to limit himself to less than 500 rwhp, running any gear taller than a 3.73 would be even less optimal. Of course, I'm optimizing based on his stated goal of running 10s, which I believe he can reach. This power and speed should support a mid-10 second run. Giving up a tenth or two in the first 60' with sub-optimal gears would hurt his chances of achieving that goal. Which is the better street gear? You're right... Totally a subjective matter. I still want to haul ass on the street, and my answer to spinning on the street is adding traction, not taking gear. 500 rwhp is very plantable.
 

·
Registered
Joined
·
536 Posts
Dwain, with your 80s, what do your AFRs look like at idle and cruise? Is the Moates QH still an EEC-IV based tuner? It was when I looked at it, if I recall correctly.
Genuine Siemens-Deka 80s are no issue with an EEC-IV and Moates QH. You could run them on a bone stock 302 and idle and driveability would be fine. I run them on a very mild H/C/I setup and you would think I had 24s. The Deka 80s break the old logic of issues of running large injectors since they have such great low pw control.

.
 

·
Registered
Joined
·
4,967 Posts
"Loading the turbo" to make the car faster is total bologna. It is especially a horrible idea with a stick shift. Two things spool the turbo, the major thing is air flow rate through the engine and the minor thing is heat. All the extra load does is slow the engine so what air mass rate the compressor is dumping runs into a bigger restriction. You see the boost go up, but it goes up because the engine is lugging.

If you have a Tremec 3550, unless you have traction issues, you probably want all the gear you can tolerate.

I have a 3200 lb turbo car with 4.10 gears. It runs about 150 in the 1/8th on a single T4 turbo. If I stick a 3.55 gear in it, the ET and MPH drop. My 60 slows, I'm not rolling as fast at the front part of the pass, and I'm not at peak power as long. My low gear boost goes up though.

As a matter of fact if I just take off in high gear my boost goes through the ceiling. In about 1.7 seconds it will go over 30 psi. The only problem is I have less torque at the back axles.

Now there certainly are cases when less rear gear ratio can help, but it isn't because you "load the turbo". One example would be if the combination of engine/converter/transmission/ and rear end has so much overall torque multiplication and the traction is so poor you just can't control spin. In a case like this the car would be much easier to deal with if something brought the torque way down.

With the stick, you likely want as much gear as you can get. Also the particular turbo and hot side construction is far more important than the bearing type for spool.
 

·
Registered
Joined
·
1,541 Posts
Genuine Siemens-Deka 80s are no issue with an EEC-IV and Moates QH. You could run them on a bone stock 302 and idle and driveability would be fine. I run them on a very mild H/C/I setup and you would think I had 24s. The Deka 80s break the old logic of issues of running large injectors since they have such great low pw control.

.
External driver box?
 

·
Registered
Joined
·
536 Posts
External driver box?
No, just my A9P with the Quarterhorse. I use Decipha's A9L2 as a base for my tune, and he even recommends going straight to the Deka 80s to avoid injector changes later (unless you outgrow those).

.
 

·
Registered
Joined
·
1,541 Posts
Well, I guess even old technology improves over time. Good deal. Good to know. If the EEC IV's are doing that well, I'll probably just use them on my next fox build.
 
1 - 13 of 13 Posts
Top