Throttle Body

Garyj92

New Member
Nov 28, 2017
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Hey got a 88 notch vortech superchsrged gt40 conversion. I guess the previous owner has been using a 65 mm motorsports throttle body thinking of upgrading to a 75mm what do you guys think? Is it better staying with the 65 am i making more power this way or is the 75 better. And is it a simple easy instal?
 
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I’d personally measure the intake port and match it as close as possible, no point in having a 75mm throttle body bottle necking to the factory 65mm opening in the intake, is it the tubular version? They I believe are 70mm
 
Yes they are an easy swap, you could also port match the opening in the intake if there’s enough to be taken out, if not just stick with the closest size to intake opening
 
No. With forced induction you won't see much if anything. The larger throttle body will make small modulation more difficult as well this impacts drivability. Imho spend money elsewhere
 
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Mine is N/A, but going from 65 to a 70mm TB then matching the upper intake, including thinning the bolt hole intrusions and blending back as far as I could, was measurable in increased tire spin and seat of pants feel. It also added a fun Whistle at idle!
 
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It's not worth the trouble.
It's 5mm, which is close to nothing.
Most intakes don't exceed 70 anyway.

And if it's a real gt40 I certainly wouldn't be home porting anything on the upper half.
 
Somewhat related...

What are the intake openings on the various "GT40" intakes? I know the explorer and gt40 mate to an EGR, but what are the opening sizes?

What size is the cobra opening?
 
I'm pretty sure they are 70mm.
Not 100% positive though.
But I did have a tubular with a 70mm TB that I know I did not port (could have been, but not by me) and it was a match.

Every time we talk about gt40 intakes, I wish I still had mine even though I don't own anything it fits on.
 
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I don't know what everyone thinks of the explorer intake but I like them. I ported mine to my 70mm throttle body and it had plenty of meat left. I've never been a fan of the cobra intake due to the integrated EGR adapter. On the stock intake a 70mm throttle body is a waste of money. You can make the hole bigger but its just a taper and it necks down too small to be worth anything for performance.
 
I actually think the explorer is underrated. Sure they are cheap and plentiful (I picked one up for the hell of it) but IIRC they featured a 75mm opening to match the egr spacer and offer the largest upper plenum volume of the three gt40 styles.

Pair it with a ported lower and i believe it would outperform the other two with decent heads. However without a ported lower I feel they are all the same really
 
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I'm pretty sure they are 70mm.

I think you are right at least with the cobra.

Taking a peek into my cobra intake through a Explorer 65mm TB I can see a tiny lip, so 70mm makes sense. Honestly I wouldn't be surprised if it was 68mm, it's barely a lip. I'll have to measure next time I have the TB off.

IMG_4263.JPG


I have a few eBay alerts set to try and snag a cheap 70mm, but it would need to be cheap to be worth the effort.
 
Somewhere on here was posted the back to back Magazine tests of the Tubular Cobra, the cast Cobra, and the Explorer. In short, the car magazine found very little difference in power between the three.

To quote this publication, "The inlet on a Cobra intake typically measures 65mm."

As did the 97 Explorer I bought (and had tmoss port the lower), and there was plenty of aluminum to open it to 70 mm.
http://www.mustangandfords.com/how-to/engine/173-0101-super/

BTW,
TMoss has a site that anyone thinking about switching intakes should check out. Here is a comparison for one of his ported ones vs a "hot" design.
http://tmoss.efidynotuning.com/GT40 Intake Capabilities2.doc
 
On my Explorer intake and my 70mm throttle body/EGR spacer I had to port it to get it to the correct 70mm size without restriction. It might be close to 70mm but its definitely not 70mm. I ported it straight in as far as I could reach. Combined with some custom sculpting to get rid of the a/c hose mount on the right front corner of the upper intake I continued the ribs all the way to the front. I think it looks good too. I also had Tmoss port the lower to my TFS heads. Throw on some paint and the stock 5.0 HO plate and it looks stock.


Here are pics of my ports Tmoss Explorer left and stock GT right. While not 1 to 1 I tried to overlay them to show the port size differences on the lowers. I don't have any pics of my throttle body opening to show.

GT40_diff.jpg
 
I have a few eBay alerts set to try and snag a cheap 70mm, but it would need to be cheap to be worth the effort.


You? :scratch: I know you didn't just turn up yesterday. :chin

At your level of scrutiny and if it were me, it would be a brand spanking new Accufab with a warranty.

I have a 75mm pp throttle body sitting on the work bench... doin nothing..

That.. is probably why. :shrug: Over the years, PP throttle bodies have been hit or miss. Most BBK were made by Whistler's Grandmother. I'll never buy another TB for a Fox that isn't an Accufab unless it's something I plan to get rid of.
 
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You? :scratch: I know you didn't just turn up yesterday. :chin

At your level of scrutiny and if it were me, it would be a brand spanking new Accufab with a warranty.

of.

Pretty much. My alert is really for a slightly used Accufab with 2 hours of idle time taken off for something else with a BIN of $50. Hasn't happened
 
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