Throttle Body VS. Spacer VS. Both

[jlogandro]

I have a 97 XJ. Stock engine with K&N cold air intake and flowmaster currently. Long term plans are to add JBA headers. I am looking to increase power and mpg (mpg when in use as DD). I have heard that the Painless Throttle Body replacement which open the bor up to a 62 mm nets about 1-2 mpg. I have also heard good/the same results from Air Raid's throttle body spacer (which is considerably less $). I understand that the TB spacer improves mpg and efficiency by vortexing the air; and the larger TB allows more air in. Should these 2 compliment each other and add a potential of 2-3,4 gains? Painless has confirmed that their TB does not vortex the air, just allows more in. They also have no idea if a spacer would further improve their TB gains. Does any one have experience with both of these or a combo of the 2? Thank you.

 

[Johnnie Walker]

Spacers are very minimal gain. An aftermarket TB should help. I know a few who have bored out the stock one for a bit of a gain. I believe there is a member over at cherokee forum that will do this for a small fee.

 

[CharlesS]

I have a 97 XJ. Stock engine with K&N cold air intake and flowmaster currently. Long term plans are to add JBA headers. I am looking to increase power and mpg (mpg when in use as DD). I have heard that the Painless Throttle Body replacement which open the bor up to a 62 mm nets about 1-2 mpg. I have also heard good/the same results from Air Raid's throttle body spacer (which is considerably less $). I understand that the TB spacer improves mpg and efficiency by vortexing the air; and the larger TB allows more air in. Should these 2 compliment each other and add a potential of 2-3,4 gains? Painless has confirmed that their TB does not vortex the air, just allows more in. They also have no idea if a spacer would further improve their TB gains. Does any one have experience with both of these or a combo of the 2? Thank you.

Since you already have the K&N FIPK installed you will find that if you install the TB spacer the hood can not be closed since the spacer will move the TB upward about an inch or so.....
I tried this same idea about 5 years ago...

Charles

 

[O-Gauge Steamer]

TB spacers really do not fo much. OK, prolly nothing. Most spacers are smooth bore and claim to increase the plenum volume. So they do. By an insignificant amount. No real improvement. The helix style that claim to create a vortex are, IMO, silly at best. Even IF they created a vortex, it would be broken up in the manifold. So, if they worked, they would create turbulance and impead air flow. So, good thing they don't work.

The 99+ Intake manifold will help the engine breath on the highway, not so much at the low end. The runners are close to the same length and it is a "dual plane" manifold. This means two exits from the plenum to the cylinders. Having curved runners the same length helps even out the air flow to the cylinders. My 98 idles better with the 99+ manifold. As for HP gain, 3HP is the accepted number for the manifold. I did notice that it ran better at highway speeds.

Bored TB. Yes, it will allow more air to flow. Will you actually notice a differnece? Hard to say. Keep in mind that increasing the intake has to be matched with increasing the exhaust. I run a header, Magnaflow Cat and a 2.5" Heartthrob Cat-Back exhaust, stock TB and a home grown Cold Air intake. Works OK. If someone had a bored TB I could borrow, I'd check to see if it makes a difference. My 97 was a 4.6 (99+ manifold and headers) and I used the TB from the 4.7 V8 on it. That and less restrictive exhaust netted me 300 dyno HP.

So, near as I can tell, unless you are making displacement, bored TBs are a questionable replacement. Problem is that most folks go by the butt dyno and if they have spent money on something they will swear it works. Human nature.

Just my .02...

 

[MrShaft696]

The spacers are kind of a waste, I had one on my chevy truck & all it did was whistle kind of loud sometimes.

 

[CharlesS]

Years ago on carbureted vehicles the spacer did actually perform a function when they were made of bakelite by insulating the carburetor from the heat of the intake manifold.

 

[cruiser54]

Get ahold of www.strokedjeep.com and see what he can do for you. I know he does an exchange on throttle bodies and is real reasonable pricewise. I've put his 60mm TBs on my Renix Jeeps and the difference was quite noticeable. But on Renix you go from 52m mto 60mm, an 8mm difference. With the HO you go from 58mm to 62mm only a 4mm difference. Might not be as noticeable.

 

[Dr. Dyno]

Here's my $0.02 on the subject:

1. I did an '01 XJ intake manifold into my 4.6 strokered '92 XJ last year. Gained 2rwhp/4rwtq on the dyno wth more torque across the whole rev range but most importantly, I gained ~1mpg so it was definitely worthwhile.

2. I fitted a TB spacer 10 years ao and reported a near 1mpg gain back then. Forget about the spinning vortex thingy; that's just a marketing gimmick. The spacer merely moves the TB blade further away from the manifold floor and allows incoming air a straighter shot into the manifold.

3. The manifold opening is 62mm so it's only natural to bolt a 62mm TB onto it. They should have done that from the factory in my view but never mind.

 

[jlogandro]

Thanks for all of the advise. I have another question... Painless also makes a TB that open up to 68 mm. This one requires you to open/shave the manifold opening to accomidate the larger bore. Has anyone tried this? This is supposed to open the flow rate to 750 cfm vs. the 600 cfm opening up to 62 does. It is not a cheap upgrade if it does not work at ~$400...

 

[CharlesS]

At a price tag of $400.... I can think of several items that I could spend that on !!
Doubt that a TB spacer enlarged to 68mm would really accomplish much to increase HP on a stock 4.0L.
Now if you were running a 4.6L stroker with a 99+ intake manifold; the investment might be worth a few ponies.
Overall... I would say its probably not worth the investment.

 

[Dr. Dyno]

I have another question... Painless also makes a TB that open up to 68 mm. This one requires you to open/shave the manifold opening to accomidate the larger bore. Has anyone tried this?

I wouldn't go 68mm unless it's attached to a high revving stroker engine. Otherwise the throttle will be too sensitive and the vehicle will buck like hell on small throttle openings especially in 1st gear. Stick to 62mm.

 

[O-Gauge Steamer]

I agree with the good Doctor about the 68mm TB. Too large for a stock motor. If someone with a Stroker wants a 68mm, they can use the TB from the 4.7 V8 out of a JY for pennies. An adapter has to be made, but I made one in my garage with hand tools... Also, the IAC motor from the XJ must be used with the V8 IAC piston. Simple swap.

 

[mflueras]

I went from stock to 62mm tb with matchin 2 inch spacer and rusty's intake. Already had free flowing exhaust. Big difference in butt dyno for me. Probably most pleased with the throttle response more than anything. There is some power gain and my mpgs went from 9 to 11 so a little better.

 

[moparmansfield]

TB spacers really do not fo much. OK, prolly nothing. Most spacers are smooth bore and claim to increase the plenum volume. So they do. By an insignificant amount. No real improvement. The helix style that claim to create a vortex are, IMO, silly at best. Even IF they created a vortex, it would be broken up in the manifold. So, if they worked, they would create turbulance and impead air flow. So, good thing they don't work.

The 99+ Intake manifold will help the engine breath on the highway, not so much at the low end. The runners are close to the same length and it is a "dual plane" manifold. This means two exits from the plenum to the cylinders. Having curved runners the same length helps even out the air flow to the cylinders. My 98 idles better with the 99+ manifold. As for HP gain, 3HP is the accepted number for the manifold. I did notice that it ran better at highway speeds.

Bored TB. Yes, it will allow more air to flow. Will you actually notice a differnece? Hard to say. Keep in mind that increasing the intake has to be matched with increasing the exhaust. I run a header, Magnaflow Cat and a 2.5" Heartthrob Cat-Back exhaust, stock TB and a home grown Cold Air intake. Works OK. If someone had a bored TB I could borrow, I'd check to see if it makes a difference. My 97 was a 4.6 (99+ manifold and headers) and I used the TB from the 4.7 V8 on it. That and less restrictive exhaust netted me 300 dyno HP.

So, near as I can tell, unless you are making displacement, bored TBs are a questionable replacement. Problem is that most folks go by the butt dyno and if they have spent money on something they will swear it works. Human nature.

Just my .02...

well said.

 

[O-Gauge Steamer]

Moparmansfield,
Thanks for the props. I have been building performance since the early '60s when I puttered about in the garage with my Dad and older Brother. In 1971, I took a very under powered '68 Triumph Spitfire from a 1.1L 4 banger to a 2.4L 6 popper. As the GT-6 and the Spit used a mostly same frame, I took a JY GT-6+ engine (1995cc) and over bored it. I then had the crank welded and offset ground to get the stroke. Custom rods and pistons... The crank was nitered and cryo'd to both releive the stress from the welding and to retemper it. Extensive head work (done with the help of a flow bench) plus a set of Weber Carbs gave the intake I needed. Headers to dual exhaust, actually a Group 44 racing part from British Leyland, back to Stebro Mufflers. Dry Sump with extenal pumps. Belt driven scavange and electric pressure. Pressure switch to prevent igniton in the absence of oil pressure for safety. Net gains? At sea level, the engine developed 255BHP @ 5KRPM and 204FtLbs torque @ 4500RPM. In a car that weighed 1900 pounds, it went much better.

I have built several 347 SBF motors. What is nice now, is that kits can be bought making it so much easier. I mean. do you have any idea how much a set of Corrilo rods and pistons cost?

Truth is, unless you are on a engine/chassis dyno, it is all perception. Some things we know do add HP. Less restrictive air cleaners, headers, Cat-backs and cats. I run all these myself.

If large HP is what you are looking for, then there is no replacement for displacement. With the caveat of forced induction which, after all, just mimics a larger displacement engine. All about moving a fuel/air mixture throught the engine.

 

[beakie]

few things I would add, having used all 3 mods mentioned by the OP (K&N CAI, spacer, 62mm TB) and the other mod mentioned (99 intake)

1. K&N and a spacer WILL hit the hood, it can be closed, but it will rub and for no change in performace (my opinion) its just ghetto looking.

2. the K&N CAI, if you measure the tubing size, is only about 60mm output... I put together a custom intake once I realized that, after I installed the 62mm TB.

3. The spacer did nothing, I left it for a few months (rubbing on the hood) just to notice anything... the whistle just got more and more annoying is all.

4. throwing another mod into the mix... the only mod I've done, that made a noticable difference was removing the clutch fan and installing an electric one. even using my poor math ability I figured about 50km (metric up here) extra per tank, and the engine ran just a touch nicer. having done the same thing on a buddies TJ... he has the same results.

 

[srmitchell]

Any opinions?
http://cgi.ebay.com/ebaymotors/Jeep...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I imagine it would make a nice difference.

 

[gradon]

The picture of the tb in the ad is for a 96+(has the nipple for the map sensor). You should be able to specify 91-95 or 96+ for HO TBs. That one has the half-shaft mod, so lets even more air in.

 

[cruiser54]

Why not just order one up from www.strokedjeep.com for $90 exchange? More than one size available, too.

 

[Darky]

Any opinions?
http://cgi.ebay.com/ebaymotors/Jeep...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I imagine it would make a nice difference.

They're trying to be sneaky with the wording..."We don't charge an annoying core charge, but if you send us your stock rebuildable throttle body, we will refund you $50!" How is that different from a core charge? Basically it's a $110 TB with a $50 core charge..Pay them $160, send your old one back, get $50 returned. :dunno: