What intake manifold??

sandman0023 · Nov 4, 2004

I am looking for the best intake manifold for my setup and future setup. I have an 89 GT. My mods are BBK 75mm throttle body, C&L 76mm mam (19lbs), BBK cold-air induction. Next Oct (waiting until then for my next bonus) I plan on buying a GT-40 crate engine and transferring these present mods over to it. I do not plan on buying a supercharger or anything like that for quite a while. I want a manifold with a 75mm opening though so I get a constant flow of air. I was leaning towards the BBK manifold but have heard a lot of negative feedback and I'm beginning to lean away from it.

MustangMulch · Nov 4, 2004

First of all, there was a thread on this exact topic like 2 days ago and i think it even had almost the exact same title. It had a good number of replies, and it can't be more than 2 or 3 pages back if that.

Second, why are you running a 75mm TB on a bone stock engine? Let me guess, you must've had a discussion with Grn92lx.

Third, where did you hear negative feedback about the BBK intake? There has only been one dyno test released, and yeah it was bogus, but that doesn't say anything bad about the intake. I don't know anyone that has it on their stang, and that is what I will be going by more than any magazine article.

So to answer your question, the RPM or RPM II intakes would be good for the gt-40 crate engine, as well as something like the TFS track heat or maybe the R-series intake, but that might be too extreme for a gt-40 crate engine.

PhLoBuS · Nov 4, 2004

Yeah I started this topic a few days ago

sandman0023 · Nov 4, 2004

Sorry. I looked back and didn't see it. I did see one close. Anyway, I read the review and read the posts in this message board about the BBK, that is when I started to second guess it.

jaidedeye · Nov 4, 2004

ya need to trade that 75mm in and get a 65 or 70. i just bought a new bbk 70mm TB and spacer. thats the biggest ill go even if i do go with a supercharger.....

for your set up i suggest the trick flow streetheat....thats what i have now with my setup.

Grn92LX · Nov 4, 2004

Get yourself a TFS street heat manifold and that 75mm TB will work just fine. It'll match that opening perfectly, I know my accufab 75mm matches just fine Let the internet racers complain, but that 75mm is NOT hurting you especially since your gonna run a manifold that will work with a 75mm. Theres a reason I run the "big" TB.

If the 75mm tb is too big and allows "too much air" in, why do guys put superchargers on stock engines? Ouch, that had to hurt

jaidedeye · Nov 4, 2004

Grn92LX

the reason i went with a 70mm is because even summit and bbk recomended that it be the biggest i could gofor my setup even if i do go forced induction. i have the trickflow streetheat as well

Grn92LX · Nov 4, 2004

Not to be rude, but they were 100% FALSE! talk to experienced people rather than sit behind the desk phone answering monkeys. Bigger TB's do NOT take away low end or whatever guys are saying. ALL THEY ARE IS ANOTHER PIECE OF THE INTAKE TRACT!! Ideally you want to run whatever TB matching your inlet or if your combo is decent port the inlet to run the bigger tb. There have been quite a few n/a 302 guys who posted GAINS from swapping from a tiny 65mm to a 75mm. Its up to you guys to find out that info or listen to inexperienced internet racers. Remember, its not my car so run whatcha want

jaidedeye · Nov 4, 2004

intermet racers? not all combo's are the same bud, whats the point of running a 75mm throtle body if its gonna get bottlenecked in a restrictive set of heads or manifold. i guess guys like michael yount an a bunch of other people on here are "internet racers" because alot of us get advice from all of them and the TB subject has come up several times before.

so how much HP have you gained from stepping up tp a 75mm TB? dyno numbers before and after?sure your motor might breath easier but it will loose velocity in the intake runners and heads. the only way i could see you gaining any kind of HP is up in the high rpms

my .02

Grn92LX · Nov 4, 2004

Not gonna argue, you think what you feel is best. I know what ed curtis recommended for me Anyway, I forget the guys name on here, but he had a bolt on 94 cobra with an edelbrock intake. he GAINED 11hp over stock 60mm TB going to a 70mm TB and then GAINED another 4hp going to the 75mm (with the edelbrock inlet port matched to fit) Thats 1 example

Another dude over on corral with a combo like mine gained about 1mph going from a 65 or 70mm (i forget) to a 75mm.

Now, im not saying the original poster needed to put a 75m tb on his stock car, BUT once he puts the manifold on it WILL work just fine.

I have no before/after dyno on my tb swap. I wasnt gonna run out and spend $150 to find out I gained 5hp across the board. I also added a new maf that day so it wouldnt have been a true comparison. What I can tell you is my whole entire inlet matches perfectly from the outlet of the maf to the manifold inlet (all perfectly 3.5") so no bottle necks what so ever

Agree to disagree, but as stated, theres a reason I swapped out my 65mm. Also got a good price on it, accufab makes nice pieces.

Mike

5spd GT · Nov 4, 2004

Grn92LX said:
Get yourself a TFS street heat manifold and that 75mm TB will work just fine. It'll match that opening perfectly, I know my accufab 75mm matches just fine Let the internet racers complain, but that 75mm is NOT hurting you especially since your gonna run a manifold that will work with a 75mm. Theres a reason I run the "big" TB.

If the 75mm tb is too big and allows "too much air" in, why do guys put superchargers on stock engines? Ouch, that had to hurt

A supercharger -otherwise known as forced induction- forces air into the intake/heads/cc...the TB allows air into the engine to certain point...by no means a "forcer"...

To big of TB can hurt you...

65mm or 70mm will flow well enough for pretty much anything you can throw at it that is streetable...and provides great throttle response....

Grn92LX · Nov 4, 2004

5spd said:
GT65mm or 70mm will flow well enough for pretty much anything you can throw at it that is streetable...and provides great throttle response....

I forget the guys name on here, but he had a bolt on 94 cobra with an edelbrock intake. he GAINED 11hp over stock 60mm TB going to a 70mm TB and then GAINED another 4hp going to the 75mm (with the edelbrock inlet port matched to fit) Thats 1 example

Not gonna argue, but i've posted a few examples of the bigger TB NOT hurting a god damn thing. You guys make the call because its your car not mine.

5spd GT · Nov 4, 2004

Grn92LX said:
Not gonna argue, but i've posted a few examples of the bigger TB NOT hurting a god damn thing. You guys make the call because its your car not mine.

Well that example doesn't say much...he switched from a stock TB to a 70mm TB (and the Performer has a 70mm opening)...and he gained 4hp from a 75mm but that last part doesn't say much either because I bet I gained 2-3hp from my cai somewhere in the rpm range though overall it didn't do anything...

shttygtstang · Nov 4, 2004

your saying to big of a tb would hurt you with even forced induction what

abought to big of an intake

i have a a victor 5.0 and a 75mm tb think that hurts with my paxton i dont

crunchie12268 · Nov 4, 2004

I have seen the dyno sheets that show a mustang with a stock, 65mm, 70mm and 75mm t/b. 65mm was a gain, but everything after that was going down significantly. But I don't know what how the car was set up internally or anything so maybe the t/b was the fault for this.

Grn92LX · Nov 4, 2004

5spd GT said:
Well that example doesn't say much...he switched from a stock TB to a 70mm TB (and the Performer has a 70mm opening)...and he gained 4hp from a 75mm but that last part doesn't say much either because I bet I gained 2-3hp from my cai somewhere in the rpm range though overall it didn't do anything...

Huh, where did I say he did a cai??? Fact is he showed gains, proof is in his pudding

5spd GT · Nov 4, 2004

Grn92LX said:
Huh, where did I say he did a cai??? Fact is he showed gains, proof is in his pudding

Lol...no I was saying that I probably gained 4hp somewhere in the powerband but in reality didn't gain anything overall...and I was trying to tie that in with the 75mm TB gain...

gtstang - I was saying that a throttle body doesn't act like a supercharger (forced induction) because the latter forces air into the engine...the throttle body doesn't so they don't act the same and therefore shouldn't have the sizes compared or the two seperate parts compared...a bigger throttle body would be better on a forced induction engine...especially with h/c/i also...

MustangMulch · Nov 5, 2004

5spd GT said:
Lol...no I was saying that I probably gained 4hp somewhere in the powerband but in reality didn't gain anything overall...and I was trying to tie that in with the 75mm TB gain...

Don't worry.. I understood what you meant. It was pretty plain english, I just think some people don't want to admit that other people's knowledge might be more accurate than their own

I totally agree with what you are saying too. Just because someone gained 4hp at one point in their RPM range doesn't mean the larger TB is benefitting their combo overall. It's all about velocity. Just because your TB matches your intake manifold inlet, that doesn't necessarily make it the right size for your application.

Michael Yount · Nov 5, 2004

You're all missing the point guys - the repeatability of ANY of the dynos isn't good enough to claim a gain as small as 4HP. Said another way, you can have that much loss/gain on back to back runs during the same strap down session. A simple air pressure change in the rear tires or an extra click on the tie down strap can change readings by 10HP or more. If the before and after readings with the throttle body change were 4HP, you don't know what happened. In fact, you could actually have lost HP, gained HP or made no difference at all.

For this guy, and for most streetable naturally aspirated 5.0L's, a 65mm t/b is plenty. You can put a bigger one on, but it won't gain you anything; and it may make small throttle modulations more difficult because the larger throttle plate allows more air to pass for a given amount of throttle travel.

I'd say go with the smallest throttle body that you know will not limit your flow - that's CLEARLY a 65mm in this case.

stang2841 · Nov 5, 2004

for a GT40 engine with a cobra intake

and a custom cam would a 65mm be ok?

what is the opening on a cobra intake?

What intake manifold??

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