Installed the 75mm TB

zenboy99 · Jul 14, 2004

94DreamGT said:
And ZenBoy...you are going by what is being said in this thread to base your decision on getting a bigger TB? I don't see any results yet...just be weary of what people are saying is all.

I've asked Ed C alot of questions over the past year, I was weary of some of his answers, but he's always been right. If he thinks a bigger throttle body will help me, then I believe him. Plus if my intake has a 70mm opening, why not go with that size of throttle body?

Another note, look at the difference in height between the throttle body and 94-95 intake adapter. That quick of a step up in that short of distance can't help optimize air flow.

Grn92LX · Jul 14, 2004

zenboy99 said:
Well...it looks like I'm going to have to order up a bigger throttle body.

Zen, consult with ed first. Keep in mind you'll have to pull the upper to port match it for a 75mm TB since the edel uppers are for a 70mm. Since its off,ask ed his thoughts on an rpm uppers AND a 75mm TB. Ed told me for my car the hot ticket was an rpm intake with a 75mm TB and we have similar set ups. You cars makes real good power and honestly it makes more mid range than mine but mine makes slightly better power up top with a slightly extended power curve. As is, there is a lot more in your car.I's say you should be hitting 110mph but the only thing hurting you is how up toip your power nose dives fast and early. The rpm and 75mm should end that problem

DougNuts · Jul 14, 2004

I'm not sure how much of a difference it would make, but technically a fox body setup has a smaller intake volume if you measure all the way to the throttle body.

If there proves to be a gain from this swap, I feel that it is because the bend is now before the throttle body rather than after it.

I'm guessing the reason people are now doing the swap is because more and more people are fixing up the SN95 cars and it takes a couple people to try it and show it can be done before it starts to catch on. Another good reason to do it is because we can now buy quality throttle bodies bigger than 65mm!

GTJake · Jul 14, 2004

94DreamGT said:
Hate to sound like a bitter person...but...

Well, you do...

JK Jeremy! I'm with ya. Not everyone needs a 75mm TB. It's what Ed told me to use and hell, he hasn't mislead me yet! To settle the debate, I gained nothing from the fox TB swap, infact, my car may have slowed down

I'm interested to see Dave's numbers, even though they won't be entirely accurate, because he's adding a bigger TB and a bigger MAF. We'll just have to wait for someone to come along and dyno with a 70mm SN setup and a 70mm fox setup. That would be awesome! Until then, DON'T SWAP TO A FOX TB!!!! I want to be one of the few with it on my car!

Jake

Rootus · Jul 14, 2004

Hopefully I'll have dyno results within a couple weeks. I'd love to do the straight across comparison, but I'm not made out of money so I need to get the bigger TB the first time around. Ed told me to get a nice big MAF and nice big TB, and like Jake said, Ed is not usually wrong.

I'm also going to try and get a new Eddy lower intake so I can have tmoss port it to match the AFR's. Then it's back to the dyno after that...

Dave

GTJake · Jul 15, 2004

Tom, you shoulda let me have my intake free for all the business I'm sending to ya!

JK

Jake

tmoss · Jul 15, 2004

GTJake said:
Tom, you shoulda let me have my intake free for all the business I'm sending to ya!

JK

Jake

Who knew?

Sorry, I work way too cheap as it is - but I will talk barter for the right parts.

zenboy99 · Jul 15, 2004

Grn92LX said:
Zen, consult with ed first. Keep in mind you'll have to pull the upper to port match it for a 75mm TB since the edel uppers are for a 70mm. Since its off,ask ed his thoughts on an rpm uppers AND a 75mm TB. Ed told me for my car the hot ticket was an rpm intake with a 75mm TB and we have similar set ups. You cars makes real good power and honestly it makes more mid range than mine but mine makes slightly better power up top with a slightly extended power curve. As is, there is a lot more in your car.I's say you should be hitting 110mph but the only thing hurting you is how up toip your power nose dives fast and early. The rpm and 75mm should end that problem

I've talked to Ed about it, but he just gave me a general answer to the question. I'm going to the NMRA Chicago race next weekend, I'm hoping to find a used RPM upper (or would the upper Typhoon intake work?) My car is a daily driver so I'm not too excited about the low-end torque I'll loose with the RPM intake.

Black95GTS · Jul 15, 2004

Here's a quick lecture on why the FOX tb swap will net you more HP, I took a fluid mechanics course this year. (Air is a fluid!) You judge the effectiveness of a pipe system based on head loss, IE, how much of the input is lost at the output.

Major head loss is what occurs in the straight section of pipes and is caused by A - the friction coefficient and B - the diameter of the pipe. Minor head loss occurs when the pipe bends, turns, loops around, and how the flow is input and output of the pipe. To determine the total head loss of the pipe system, you add up the two.

To determine the Major head loss, it is generally accepted to use the Darcy Equation, which is Head Loss = (Friction Constant)*(Length of pipe / Diameter of pipe) * (velocity ft/s^2 / 2*gravity).

To determine the Minor head loss, use the derived Darcy equation MHL = (sigma of all friction coefficients) * (velocity ft/s^2 / 2*gravity).

The sigma is all of the friction coefficients added together. A friction coefficient is extremely important when the pipe sections are close together and short in length. In longer pipe sections the coeficient decreases. In a 20 inch section of pipe, they are not very important.

You can see how the larger the diameter of pipe, the smaller the major head loss would be. The longer you can sustain the largest diameter possible, the more fluid will flow more efficiently. Conversely, the slightly higher angled bend in the Fox TB will have an almost negligible negative effect.

Ultimately, you will gain more with the Fox TB.

TMC · Jul 15, 2004

zenboy99 said:
I've talked to Ed about it, but he just gave me a general answer to the question. I'm going to the NMRA Chicago race next weekend, I'm hoping to find a used RPM upper (or would the upper Typhoon intake work?) My car is a daily driver so I'm not too excited about the low-end torque I'll loose with the RPM intake.

Stop by the Stangcrazy.com pits at that race and I'll give you an earfull in person about why I would use the 75mm TB.

BTW guys - I used a 75 on my 95 with an elbow not the fox conversion. I didn't make the most power of any of these guys but it worked good for me.

http://home.comcast.net/~nmrastocker/95GT.html

zenboy99 · Jul 15, 2004

Sounds good Troy, I'll try to find you.

tmoss · Jul 15, 2004

Troy, numbers aside, your torque curves were pretty consistant in key events between the two dynos. On the second one, the A/F goes to richer right when the dip occurs in the torque. I've seen this charataristic in other dynos too (EDC's tend to have them), and I wonder if it's a function of the cam or the intake - or both - or what?. Do you match and align the intake port with the head during assembly? Ever tried pulling the vaccum from the regulator and setting fuel for race consditions for a WOT dyno pull? It seems to be occuring in the rpm band where your peaking VE.

TMC · Jul 15, 2004

tmoss said:
Troy, numbers aside, your torque curves were pretty consistant in key events between the two dynos. On the second one, the A/F goes to richer right when the dip occurs in the torque. I've seen this charataristic in other dynos too (EDC's tend to have them), and I wonder if it's a function of the cam or the intake - or both - or what?. Do you match and align the intake port with the head during assembly? Ever tried pulling the vaccum from the regulator and setting fuel for race consditions for a WOT dyno pull? It seems to be occuring in the rpm band where your peaking VE.

I'm not sure what it is a function of but sure wish I did. The way the TQ curve looks before that dip you would think the car would make more TQ if it continued up rather than stumbling like it does. To be honest I never really tried to clean that up as the car was never really dyno tuned, but rather just made a couple pulls to see what kind of power it was making. With more testing I may have been able to do something with it but I can't say for sure what may have changed it.

I don't ever use the vacuum line on the regulator. That's just one more variable that you don't have direct control over IMO and I didn't have an adjustable FPR on the car so there wasn't too much I could do.

tmoss · Jul 15, 2004

The torque curve is a reflection of how well the cylinder is filling assuming everything in the EEC/ignition is working correctly. Two of my customers MatZ281LE (Cobra/AFR165) and GTJake (Performer/AFR165) had very smooth torque curves, Matt used a Crower 15511 cam and Jake used ED's cam. I'd take a serious look and the intake tract and be sure there are no reasons for flow to be affected by misaligned flanges, gaskets, or anything else when you get a chance. Do you have a data logging or tuning device? Are you running the factory spark curves in the EEC? Which EEC is it?

TMC · Jul 15, 2004

tmoss said:
The torque curve is a reflection of how well the cylinder is filling assuming everything in the EEC/ignition is working correctly. Two of my customers MatZ281LE (Cobra/AFR165) and GTJake (Performer/AFR165) had very smooth torque curves, Matt used a Crower 15511 cam and Jake used ED's cam. I'd take a serious look and the intake tract and be sure there are no reasons for flow to be affected by misaligned flanges, gaskets, or anything else when you get a chance. Do you have a data logging or tuning device? Are you running the factory spark curves in the EEC? Which EEC is it?

I'm certain there was no misalignment in the intake or exhaust ports. I'm pretty anal about that stuff. I even had the intake milled with the heads to assure they would line up. And I ground the weld out of the headers and rewelded them around the outside to be sure that is a smooth transition.

It's the stock EEC (T4MO I think?) and I don't use the EEC for timing, I lock the dist. out.

I won't be looking into that problem area any time soon as I've already taken that combo out of the car. I'm dreaming up something new to build over the winter

tmoss · Jul 16, 2004

So, you run total timing from start to finish? How much total advance do you run? Ever try running less? I'm sure you've done this kind of experimentation, but I'm just curious. It's good to take a few degrees timing out near peak torque rpm band (Peak VE) because you don't need as much timing there and igniting a little later might remove the potential for pressure building to a detrimental point while the piston is still rising. Either side of the Peak can take more timing, but a few degrees pulled out near peak can mean more power there. One of the benefits of the tuner is the ability to customize the spark curve - although there are many other benefits. Gonna use one in the future?

GTJake · Jul 16, 2004

I'm kinda curious as to what TMC runs for total timing as well. I'm running 42* advanced with the tweecer. What would that be comparable to with the spout in, 18*?

Jake

TMC · Jul 16, 2004

tmoss said:
So, you run total timing from start to finish? How much total advance do you run? Ever try running less? I'm sure you've done this kind of experimentation, but I'm just curious. It's good to take a few degrees timing out near peak torque rpm band (Peak VE) because you don't need as much timing there and igniting a little later might remove the potential for pressure building to a detrimental point while the piston is still rising. Either side of the Peak can take more timing, but a few degrees pulled out near peak can mean more power there. One of the benefits of the tuner is the ability to customize the spark curve - although there are many other benefits. Gonna use one in the future?

Although you are correct with this idea in reality the limited control that you have with the EEC (even with most tuners) makes it very difficult to go faster than just locking the timing out at the proper advance. Believe me, I've tried both ways and always been happier without the EEC in the picture. In the past on the Factory Stock car and other street cars I've used the PMS trying to control timing better but never been able to get the desired effects. At present the only thing I've used that I feel is acurate enough to control timing is the MSD digital 7 box and I still would lock the dist out and pull timing where I would want to with that unit rather than through the EEC.

Power adder cars are a little different but I've seen many cars with nitrous and blowers that also run very well with the dist locked. However I wouldn't suggest that for a street car with a power adder.

TMC · Jul 16, 2004

GTJake said:
I'm kinda curious as to what TMC runs for total timing as well. I'm running 42* advanced with the tweecer. What would that be comparable to with the spout in, 18*?

Jake

42° at WOT?

With a stock EEC that would be in the 24-26 range depending on sensor readings.

AFR heads need more timing than TFS TW heads as a general rule so we shouldn't really be comparing them.

zenboy99 · Jul 16, 2004

TMC said:
AFR heads need more timing than TFS TW heads as a general rule so we shouldn't really be comparing them.

Is there a reason for this? I've never heard this before.

Installed the 75mm TB

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