throttle bodies

Performance mods and Advanced Stroker discussion.
wjtom
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throttle bodies

Post by wjtom »

Ok ive seen this brought up many times one here.Stock dodge 4.7 is 65mm and 2001up is 68mm. Cubic inches is cubic inches doesnt matter how you got there.Whether it has 2 cylinders or 12.Performance throttle bodies for these are 70-72mm.So there is no reason it shouldnt work for us and it does work.I know many have thought it would be too responsive. I have no problems with mine as far as drivability goes and this sees 365 days a year regardless of weather.62mm throttle bodies were made for a stock or mild 4.0 upgrade not a stroker.
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SilverXJ
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Re: throttle bodies

Post by SilverXJ »

I can't agree. I have the 63mm throttle body and any more would be way too responsive. That and I am already lugging the engine before the transmission wants to kick down. The reason the 4.7L and most engines can get away with a larger throttle body without this issue is because their linkage utilizes a cam to make the cable appear longer on the low throttle inputs. Even the 5.2l/5.9L engines have this. The 4.0L does not and its just a straight pull. A complete new throttle body and accelerator cable would fix this, but no one makes that.

While a larger throttle body would be beneficial for the upper RPMs there is no throttle body/throttle cable setup capable of correctly modulating the throttle pull at low pedal input.

While one may think this can be tuned out the only way would to be to pull back timing, and that is just a bandaid.
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Cheromaniac
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Re: throttle bodies

Post by Cheromaniac »

wjtom wrote:Ok ive seen this brought up many times one here.Stock dodge 4.7 is 65mm and 2001up is 68mm. Cubic inches is cubic inches doesnt matter how you got there.
The required TB size doesn't just depend on ci displacement. It also depends on the maximum rpm that you'll be using.
For a 4.6L stroker that's limited to 5200rpm, a 65mm TB would be more than adequate.
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
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wjtom
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Re: throttle bodies

Post by wjtom »

Cheromaniac wrote:
wjtom wrote:Ok ive seen this brought up many times one here.Stock dodge 4.7 is 65mm and 2001up is 68mm. Cubic inches is cubic inches doesnt matter how you got there.
The required TB size doesn't just depend on ci displacement. It also depends on the maximum rpm that you'll be using.
For a 4.6L stroker that's limited to 5200rpm, a 65mm TB would be more than adequate.
I realize that.Mines not limited to 5200.As are alot of other builds.But i guess until somebody else tries one we could argue this all day.
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Re: throttle bodies

Post by Cheromaniac »

wjtom wrote:I realize that.Mines not limited to 5200.As are alot of other builds.But i guess until somebody else tries one we could argue this all day.
if your stroker is capable of surviving 6000rpm you could use a 70mm TB.
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
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ccpanel
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Re: throttle bodies

Post by ccpanel »

just do the math;

http://www.lxforums.com/board/showthrea ... Calculator

insanely hard math
http://dairally.net/daihard/chas/MiscCa ... rottle.htm

basic carb calc at 5,000 @ .85% yeilds 350cfm carb no more than 450 @100%
http://www.gtsparkplugs.com/CarbCFMCalc.html

some flow tests from university.
no RPM given but does not matter-you can see that a 48mm TB will flow over 700CFM so a stock TB at 60 would flow... 1,000?
http://www.gmtuners.com/flow/index.htm

when Stock 3800 vin L throttle body w/ screen -- 419.1 cfm you can be sure that stock jeep is perfectly fine.

also keep in mind-the bigger the TB-the slower the air speed which could mean less air jammed into cylinder=less power.
wjtom
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Re: throttle bodies

Post by wjtom »

ccpanel wrote:just do the math;

http://www.lxforums.com/board/showthrea ... Calculator

insanely hard math
http://dairally.net/daihard/chas/MiscCa ... rottle.htm

basic carb calc at 5,000 @ .85% yeilds 350cfm carb no more than 450 @100%
http://www.gtsparkplugs.com/CarbCFMCalc.html

some flow tests from university.
no RPM given but does not matter-you can see that a 48mm TB will flow over 700CFM so a stock TB at 60 would flow... 1,000?
http://www.gmtuners.com/flow/index.htm

when Stock 3800 vin L throttle body w/ screen -- 419.1 cfm you can be sure that stock jeep is perfectly fine.

also keep in mind-the bigger the TB-the slower the air speed which could mean less air jammed into cylinder=less power.


First off the 48mm throttle body you are talking about has 2 plates not one.Yes 2 48mm plates.Second dont use carb calculators for throttle bodies it doenst work the same.Throttle bodies dont need a good signal to work properly a carb will always be smaller.That would be true with the bigger throttle body when it is too big.Bigger throttle body helped everywhere.I have installed a 68mm on a bone stock jeep and it was a noticable improvement.Just to see what happened before the new motor went in.
wjtom
I made it to triple digits!
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Re: throttle bodies

Post by wjtom »

Cheromaniac wrote:
wjtom wrote:I realize that.Mines not limited to 5200.As are alot of other builds.But i guess until somebody else tries one we could argue this all day.
if your stroker is capable of surviving 6000rpm you could use a 70mm TB.
Nobodies motor is going to come apart if just because you turned it higher than 5300rpms if properly assembled with good parts.Every motor has a harmonic at some point just dont hang there.Many 5500-6000rpm runs over 3 years.No problems.I think the harmonic thing is blown out of proportion.This is performance tech right?
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Re: throttle bodies

Post by FlyinRyan »

Alright, stop, collaborate and listen....

Calculators do not spec motors, last I checked. (short of using PipeMax or something serious). Opinions formulated on real world experience does.
Even a garden variety 4.6 needs more than a 62mm TB. This is fact, not opinion. End result is approx ~2.5-3" vacuum at WOT. Don't believe me? BRB, I have a hard drive full of datalogs showing this.
I have never encountered a 270hp truck that was too responsive???
Most strokers will still show restriction at higher rpms with a 65mm TB.
TB size is dictated by one thing, airflow requirement. (Which is a function of RPM and VE)
Even the 3.6 Pentastars are using a 74mm TB STOCK, and yes they do respond well to TB porting!
I am usually pretty insistent on the strokers I tune having a proper size TB - never have I heard someone tell me "Wow, I think my 62mm felt better"???
Same with exhaust, 3" should be standard on a stroker.

Some of the tech here lately is downright unsafe- stock plugs, 87 octane usage with strokers- and some of it is just plain wrong for making power. People are spending good money to build these things, the least we can do is set them all up for success.

I did a 10.2:1 4.6XJ with a 4.7 TB that was ported to a 71x81mm as per my specs, it had no problem putting SBC race trucks back on the trailer at the mud drags, then getting 20mpg on the highway on the drive back home. This was on 35s and 4.56s too.

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Re: throttle bodies

Post by Cheromaniac »

FlyinRyan wrote:Alright, stop, collaborate and listen....
Ice ice baby............. ;)
FlyinRyan wrote:Some of the tech here lately is downright unsafe- stock plugs, 87 octane usage with strokers- and some of it is just plain wrong for making power.
AFAIK I'm the only one still using stock Champion RC12LYC plugs but since I live in a hot climate, I also use 91 octane gas most of the time.
Those who want to use 87 octane gas are building low compression motors and don't care about big HP numbers. They're mostly on a limited budget and just want something better than stock.
wjtom wrote:Nobodies motor is going to come apart if just because you turned it higher than 5300rpms if properly assembled with good parts.Every motor has a harmonic at some point just dont hang there.Many 5500-6000rpm runs over 3 years.No problems.I think the harmonic thing is blown out of proportion.This is performance tech right?
Indeed it is. If you spend the cash on the right parts, proper assembly, and nitride the crank, 6000rpm shouldn't be a problem and like you said, you can drive through the 5600-5700rpm harmonic. The thing is that most of us have built mild strokers whose torque curves are dropping off past 4500rpm and there's little point in going beyond the factory 5200rpm rev limit.
The beauty is that there's a plethora of parts available to build a stroker any way you like, and we're grateful to have FlyinRyan around to tune in more radical set-ups.
1992 XJ 4.6 I6 - 5MT - Stroker build-up, Stroker "recipes" Sold
1995 Mustang GT - 4AT - Modded Sold
2006 Mustang GT - 5MT - Modded Midlife Crisis Car :mrgreen:
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ccpanel
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Re: throttle bodies

Post by ccpanel »

wjtom wrote:
ccpanel wrote:just do the math;

http://www.lxforums.com/board/showthrea ... Calculator

insanely hard math
http://dairally.net/daihard/chas/MiscCa ... rottle.htm

basic carb calc at 5,000 @ .85% yeilds 350cfm carb no more than 450 @100%
http://www.gtsparkplugs.com/CarbCFMCalc.html

some flow tests from university.
no RPM given but does not matter-you can see that a 48mm TB will flow over 700CFM so a stock TB at 60 would flow... 1,000?
http://www.gmtuners.com/flow/index.htm

when Stock 3800 vin L throttle body w/ screen -- 419.1 cfm you can be sure that stock jeep is perfectly fine.

also keep in mind-the bigger the TB-the slower the air speed which could mean less air jammed into cylinder=less power.


First off the 48mm throttle body you are talking about has 2 plates not one.Yes 2 48mm plates.Second dont use carb calculators for throttle bodies it doenst work the same.Throttle bodies dont need a good signal to work properly a carb will always be smaller.That would be true with the bigger throttle body when it is too big.Bigger throttle body helped everywhere.I have installed a 68mm on a bone stock jeep and it was a noticable improvement.Just to see what happened before the new motor went in.
I spent all of 2 seconds finding links and didnt don a lab coat, nor do I claim or otherwise pretend to be informed.

BUT... just cause a calc says you only need a 350 carb for a 280 motor... doesnt mean people dont put MUCH bigger carbs/TB on motors...

and it doesnt mean that bigger carbs/TB are not better.

You would think that if a bigger TB does not 'feel' better on the pants dyno-companies wouldnt be able to sell them.
so-just thought I would put those links out there for you guys to look at.

or google your own.

just let the math do the talking...
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ccpanel
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Re: throttle bodies

Post by ccpanel »

Cheromaniac wrote:
FlyinRyan wrote:Alright, stop, collaborate and listen....
Ice ice baby............. ;)



Indeed it is. If you spend the cash on the right parts, proper assembly, and nitride the crank, 6000rpm shouldn't be a problem and like you said, you can drive through the 5600-5700rpm harmonic. The thing is that most of us have built mild strokers whose torque curves are dropping off past 4500rpm and there's little point in going beyond the factory 5200rpm rev limit.
The beauty is that there's a plethora of parts available to build a stroker any way you like, and we're grateful to have FlyinRyan around to tune in more radical set-ups.

I agree-I feel the best bang/buck you can do on ANY motor is to have it professionally balanced.
every rotating part.

BTW-dont assume brand new parts are good, my machinist rejected 3 brand new harmonic balancers from a quality place before the 4th would be able to be balanced. These were not pep boys balancers-these were supposedly upgraded hot rod nice ones, yet it took 4 of them before one was found to not be completly junk.

so now my motor is +/- 1 gram and you can tell in throttle response and smoothness.
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SilverXJ
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Re: throttle bodies

Post by SilverXJ »

ccpanel wrote: BTW-dont assume brand new parts are good, my machinist rejected 3 brand new harmonic balancers from a quality place before the 4th would be able to be balanced. These were not pep boys balancers-these were supposedly upgraded hot rod nice ones, yet it took 4 of them before one was found to not be completly junk.
One reason I went with the ATI. One balancer had a wobble (not weight related, but bent), one's outer ring slipped and I can't remember the problem with the third.
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ccpanel
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Re: throttle bodies

Post by ccpanel »

SilverXJ wrote:
ccpanel wrote: BTW-dont assume brand new parts are good, my machinist rejected 3 brand new harmonic balancers from a quality place before the 4th would be able to be balanced. These were not pep boys balancers-these were supposedly upgraded hot rod nice ones, yet it took 4 of them before one was found to not be completly junk.
One reason I went with the ATI. One balancer had a wobble (not weight related, but bent), one's outer ring slipped and I can't remember the problem with the third.
Those problems with OEM or with the ATI?

What about a hesco kit for those of us who arent/cant use flexplate CPS?
those balancers junk or okay?
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SilverXJ
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Re: throttle bodies

Post by SilverXJ »

ccpanel wrote:Those problems with OEM or with the ATI?
OEM style. The ATI unit is very high quality. Its also rebuild-able and will be the last balancer I ever buy for this engine.
What about a hesco kit for those of us who arent/cant use flexplate CPS?
I would hope the balancers that Hesco uses doesn't have those problems. I do know they offer a pinned balancer, so I would hope they use one of those for their balancer for the CPS.
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