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63mm Throttle Body Installation Question

jls095

NAXJA Forum User
Location
MA
I’m considering buying a 63mm throttle body from Leigh Performance to complement my new Borla exhaust. First off, is this a worthwhile upgrade?
Second, I reviewed the installation procedures for the Jeepers and Creepers TB and at one point they have you trim a section of the throttle shaft with a hacksaw. (Step 9 in link below)



http://www.jeepersandcreepers.com/media/62mm_Throttle_body_kit_installation_instructionspdf.pdf


Is this a part of the installation for Leigh Performance TB’s? I hadn’t ever heard anyone mention this before when installing a bored TB.
 
"62mm Throttle Body
Myth: The factory 60mm throttle body is a choking point in the stock engine. Boring the factory throttle body or installing a larger-bore aftermarket throttle body will allow the engine to breathe and make more power.
Our Thoughts: On most stock or slightly modified engines the factory 60mm throttle body isn't the cork, and is capable of supplying the engine with enough air to get the job done. Only on a vehicle with airflow modifications like a cold air intake and free-flow exhaust will you notice a difference.
Claimed Gains: 10-20hp
Actual Gains: 5hp
Notes: We did see a 5hp difference with a 62mm throttle body on a 4.0L with a cold air intake and exhaust modifications and believe the increase would be larger with other airflow enhancements, like a larger camshaft or high-flow cylinder head. It's a complementary component best used in concert with other products."*

*FROM JP MAGAZINE UNDER FAIR-USE GUIDELINES.*

So, with a little more open exhaust you should see a LITTLE improvement. To get the most out of it you would need a cold-air intake, performance cam, polished and ported head, and then change the values of a couple of sensors.

IMHO you would get more kick out of better gearing.
 
The throttle body is not snake oil. Jeff's needs no modification to a throttle shaft or anything. Its a bolt on affair.

A larger throttle body will give you better throttle response and slightly more high RPM power and through the band. For a modification like this (and many others) peak HP and torque changes are quite meaning less. Its the area under the curve that is more important rather than peak.

Quoting JP Magazine.. lol
 
The throttle body is not snake oil. Jeff's needs no modification to a throttle shaft or anything. Its a bolt on affair.

A larger throttle body will give you better throttle response and slightly more high RPM power and through the band. For a modification like this (and many others) peak HP and torque changes are quite meaning less. Its the area under the curve that is more important rather than peak.

Quoting JP Magazine.. lol


I too have read the entire article in JP magazine. My opinion is,...except for the morons who experimented with a jeep 4.0L, every one who did bolt on mods the their 4.0L saw some gains. Modest gains? Yes but gains none the less. Every other forum and every other vehicle I have read about saw gains by installing a larger throttle body on top of a replaced free/er flowing intake manifold. All except JP magazine.

In the case of our 4.0L engine, there is no reliable record of increased HP. There is on the other hand numerous articles of increased throttle response and quicker acceleration. No, there is no gain on the top end (RPM) but since most of us do not run the 4.0L in the top RPM range getting out of the hole faster is well worth the cost of bolt on parts.

Do not read too much into the articles form JP magazine. I stop subscribe to them simply because their findings are not the same as most other people I have heard about.
 
As is always the case, one has to look at the engine as a complete system designed to pump air. Can a larger TB flow more air? Most certainly it will. The question to ask is, will it flow more air.

There is a very simple test that you can run that will identify any choke points in the intake track.

The test uses a vacuum gauge which can be purchased for very little money, Plug the gauge into the intake manifold and run the engine to WOT. This is done in the driveway, do not need to be on the road.

If the gauge reads 5"Hg or less at WOT, do not do anything as there will not be any performance gains made.

At WOT, the manifold should "drop" (it actually rises...) to ambient atmospheric pressure. So, the vacuum gauge, ideally, would read 0"Hg.

If the reading is above 5"Hg, then the culprit must be found. Disconnect the TB from the air tube going to the stock air box (assuming you still have one) and rerun the test. If the gauge now reads under 5"Hg, then the filter is the issue.

If and it is unlikely on a stock engine, the gauge still reads above 5"Hg with an open TB, the TB is a choke point.

Not to long ago, I ran this test on my rig and found that the TB had to be replaced. In my case, it required a 68mm tB to resolve the choke point. My Jeep is Supercharged and that is why the large TB.

Folk that have gone the stroker route would be advised to run this test as the stock TB is not all that great after 4.5L of displacement.

Keep in mind that the stock TB actually necks down to 58.5mm (if memory serves) under the butterfly. IMO, that is the true size of the TB. Bored TBs remove the neck as well as open up everything else.
 
Quoting JP Magazine.. lol

To each their own.

Instead of "lol" how about you post some links to other articles that MEASURED THE HP GAINS of a larger throttle body with something other than their ARSE?
 
JP Magazine is more of a hack than anything else and notorious for getting facts and figures wrong. I'd take no data over their crap any day. However, I know what a throttle body does and I don't need any crap data to tell me that. Peak HP isn't everything.
 
I’m considering buying a 63mm throttle body from Leigh Performance to complement my new Borla exhaust. First off, is this a worthwhile upgrade?
Second, I reviewed the installation procedures for the Jeepers and Creepers TB and at one point they have you trim a section of the throttle shaft with a hacksaw. (Step 9 in link below)

http://www.jeepersandcreepers.com/media/62mm_Throttle_body_kit_installation_instructionspdf.pdf


Is this a part of the installation for Leigh Performance TB’s? I hadn’t ever heard anyone mention this before when installing a bored TB.

The Jeepers and Creepers throttle body is an entirely new piece and considered a do it yourself kit. It reuses components from the old throttle body that have to be modified slightly. Leigh Performance and other companies do all the work for the customer.

As O-Gauge Steamer said the engine is an entire system. If a larger throttle body is put on to move more air then the rest of the engine needs to be able to move more air. That includes exhaust, intake manifold, and the runners in the cylinder head.
 
The Jeepers and Creepers throttle body is an entirely new piece and considered a do it yourself kit. It reuses components from the old throttle body that have to be modified slightly. Leigh Performance and other companies do all the work for the customer.

As O-Gauge Steamer said the engine is an entire system. If a larger throttle body is put on to move more air then the rest of the engine needs to be able to move more air. That includes exhaust, intake manifold, and the runners in the cylinder head.

I know I havent been around long but did you just use the words "entirely new piece" and "old throttle body" to describe the same part?????
 
This is what you get with the J&C throttle body:
IMG_1038.JPG

The housing, a new butterfly plate and two screws.

From your old throttle body you use everything else. Some assembly required.

On the Leigh Performance one all you need to do is swap over your sensors and bolt it on.
 
I run an F&B http://www.fbthrottlebodies.com/ Throttle Body and they are also machined out of billet aluminium.

But, as has been suggested, unless the engine requires a larger TB, just putting one on will only make you move faster as you wallet will be lighter...

IMO, no need to change unless the exhaust has been improved and/or a camshaft replacement has occurred. Usually, installing a performance cam also mandates that the exhaust be less restrictive.

My suggestion, for what it is worth, is to start with verifying what you have. Determine where you want to go the engine in terms of development and set the budget. Then, stay to the plan.
 
Yes, but yours isn't 62mm. There is a place for an expensive billet piece. This isn't it.

His link shows two TBs for the Jeep 4.0--one is 62 mm, the other is 68 mm.

Am I missing your point?
 
I think his point is that the 62mm TB is nearly $400... It's definitely an expensive billet piece...

But he specifically said it isn't 62 mm, and as it is either 62 or 68 I wasn't catching his point.
 
OGS runs an oversized throttle body on his super-charged XJ. $400 on a modified engine? Sure. $400 for a stock motor with a header? I wouldn't, when you can remove the taper in a stock throttle body for $5, or get one bored out for what, $150? Hell, maybe I'm missing the point. I don't really know. The billet pieces are pretty, but I don't think they would provide good bang-for-buck.
 
OGS runs an oversized throttle body on his super-charged XJ. $400 on a modified engine? Sure. $400 for a stock motor with a header? I wouldn't, when you can remove the taper in a stock throttle body for $5, or get one bored out for what, $150? Hell, maybe I'm missing the point. I don't really know. The billet pieces are pretty, but I don't think they would provide good bang-for-buck.

Billet are just for show at the 62mm/63mm size. My bored out stock version is powder coated red. Again, for show, but it only was a $10 or $20 option on top of a $100 price point.
 
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