best throttle body spacer

[Dr. Dyno]

My experience of the Poweraid TB spacer is that it does produce a small gain in low/medium rpm torque but you'd have to do several before-and-after acceleration runs timed with a stopwatch to measure any difference. Otherwise the difference is too small to notice by the SOTP and that's why many who've tried it think it's useless.
Since a TB spacer can be found for something like $30 on e-bay, it's definitely worth a try.
The factory intake system leaves a lot to be desired and the stock 4.0 only reaches a maximum volumetric efficiency of 75% (225lbft from 4.0 liters is pretty dismal by today's standards) so there's a lot of room for improvement.

 

[MaXJohnson]

My experience of the Poweraid TB spacer is that it does produce a small gain in low/medium rpm torque but you'd have to do several before-and-after acceleration runs timed with a stopwatch to measure any difference. Otherwise the difference is too small to notice by the SOTP and that's why many who've tried it think it's useless.
Since a TB spacer can be found for something like $30 on e-bay, it's definitely worth a try.
The factory intake system leaves a lot to be desired and the stock 4.0 only reaches a maximum volumetric efficiency of 75% (225lbft from 4.0 liters is pretty dismal by today's standards) so there's a lot of room for improvement.

You measured the small gain with a stop watch? The stop watch determined that it was in the low/medium RPM range? The "maximum" 75% VE figure comes from where?

 

[atx xj]

i like you johnson...you trust nothing. good man. what i was saying is that if i were to try and effectively increase my engines power through intake modifications, i would start by first allowing a greater intake efficiency by boring/obtainging a wider throttle body. From my elementary understanding, the pressure difference, which a throttle body spacer in effect targets, is not going to be greatly altered by the addition of such a small amount of space, and most definitly nothing good will come of a "helix bore" super duper hippity hoppity spacer priced "affordably" at 199, or whatever thats at. I wont claim to be an expert on the mathematical effects of a TB spacer v.s. a bored t.b. but i can guarantee that you will notice an improvement with a bored tb, while i most certainly could not feel a difference with the spacer on my friends 96 grand with the I6 in it with a poweraid spacer. Keep in mind i only work on cars, i dont design them (yet).

 

[ren]

Okay, question, since this thread has gone from a T/B question to VE improvement, Why not use a double T/B set-up similar to what HESCO had as a teaser on their site, AND a certain XJ ( i think it was an early '90's model, but it was originally factory sponsored) that is STILL kickin' tail in SCORE events use? This is a do-able thing since it is used in off-road desert racing, but I think the PITA is going to be figuring out low to mid throttle ECU issues. Just some thinking going on here, since I am learning about EFI systems and thier capabilities/limits. So, if you people would be so kind, go easy on any flaming on me, like I said, I am starting to learn about this EFI stuff.
Ren

 

[John(XJ)Jeep]

You measured the small gain with a stop watch? The stop watch determined that it was in the low/medium RPM range? The "maximum" 75% VE figure comes from where?

I'm guessing the time it takes to get to a certain speed at different RPM starting points. His comment on VE is pretty much self explainitory.

 

[MaXJohnson]

Okay, question, since this thread has gone from a T/B question to VE improvement, Why not use a double T/B set-up similar to what HESCO had as a teaser on their site, AND a certain XJ ( i think it was an early '90's model, but it was originally factory sponsored) that is STILL kickin' tail in SCORE events use? This is a do-able thing since it is used in off-road desert racing, but I think the PITA is going to be figuring out low to mid throttle ECU issues. Just some thinking going on here, since I am learning about EFI systems and thier capabilities/limits. So, if you people would be so kind, go easy on any flaming on me, like I said, I am starting to learn about this EFI stuff.
Ren

Hesco has a dyno print-out on their site showing the throttle body spacer returns a ~4% gain in HP and torque over a stock 4.0. The graph is a little puzzling though, since it shows the stocker developing 223 HP and 262 ft/lbs of torque. With these numbers, you can logically assume they have already massaged the stocker somewhat. Does the spacer work better due to these unknown mods? You really can't tell from the info on their site. Hesco has the equipment and expertise to offer some very specific results for the spacer as well as detail on the procedures used to obtain the results, yet they don't provide anything but a questionable dyno graph.

I'm guessing the time it takes to get to a certain speed at different RPM starting points. His comment on VE is pretty much self explainitory.

Impressive response. I'll add it to my John(XJ)Jeep collection:

"I found out what scavenging is exactly and I can tell that I don't want it."
John(XJ)Jeep

"I can hit 240kph149MPH @ 6500 in 4th gear with my Jeep right now and have a dozen witnesses that say I did."
John(XJ)Jeep

"Its' not a stroker and on top of that I can rev and hold 6500 rpm any higher and it starts to vibrate if under load, idle is different story but I can hold it longer but I don't like to do just because. I would never hold it at that rpm for more than a few seconds or so under load. Heres a hint though on what could have been done, it is a special built show model or should I say once was. Its power output is higher than factory roll-off Jeeps, considerably. I got lucky I guess."
John(XJ)Jeep

"6500 RPM is unbelievable to some of you folk eh? Its nothing for me. I can blip the gas and it reaches 4000. It sounds like you haven't seen that high in a Jeep engine. I bet most of you are scared of even thinking going 4500 RPM.
Look, you just got regular factory engines that you have to deal with... I don't. Simple as that. Deal with it."
John(XJ)Jeep

"I can write and type much better than a 13 year old."
John(XJ)Jeep

 

[roXJeepr]

Consider that factory engineers designed the cam, ports, intake runners, plenum, throttle body, air tube and air box as a tuned system to be most efficient in the heart of the power band.

In most cases I would agree. But in the XJ/MJ I believe they designed it just so that it would fit in that cramped-ass engine compartment. :laugh3:

But for real, to the original poster, even if the spacer was $5 shipped... I wouldn't waste my money on it.

 

[DCB]

It is my understanding that the later years, not sure of the dates, have larger TB to match the intake... so a spacer would be a waste of $$ for the them. If you bored the stock TB on the older XJ's it should make a difference.
Peace

 

[John(XJ)Jeep]

Impressive response. I'll add it to my John(XJ)Jeep collection:

"I found out what scavenging is exactly and I can tell that I don't want it."
John(XJ)Jeep

"I can hit 240kph149MPH @ 6500 in 4th gear with my Jeep right now and have a dozen witnesses that say I did."
John(XJ)Jeep

"Its' not a stroker and on top of that I can rev and hold 6500 rpm any higher and it starts to vibrate if under load, idle is different story but I can hold it longer but I don't like to do just because. I would never hold it at that rpm for more than a few seconds or so under load. Heres a hint though on what could have been done, it is a special built show model or should I say once was. Its power output is higher than factory roll-off Jeeps, considerably. I got lucky I guess."
John(XJ)Jeep

"6500 RPM is unbelievable to some of you folk eh? Its nothing for me. I can blip the gas and it reaches 4000. It sounds like you haven't seen that high in a Jeep engine. I bet most of you are scared of even thinking going 4500 RPM.
Look, you just got regular factory engines that you have to deal with... I don't. Simple as that. Deal with it."
John(XJ)Jeep

"I can write and type much better than a 13 year old."
John(XJ)Jeep

Wow, your still angry at me? Well I'm pretty sure every other being that read my other posts are too. Seeing that your pissed and everyone MUST agree with you. I don't think your way of showing how superior you think you are is not a very smart thing to do because I can automatically tell what kind of person you are.

1. I still don't want scavaging because my application still does not fit it.

2. I can still hit 240 in forth and I AM willing to put money down that your
4000 pound clunker coudn't touch me. And that's what's pissing you off.

3. I'm sorry that you are stuck at 5200 on your Jeep maybe some day you
will overcome that. Oh yeah, just because you bought yours from the
back from some garage doesn't mean that everyone else did too.

4. It's not like this is the first that it has ever happened, many cars were
lowballed when they came off the lot to combat high insurance rates for
powerfull cars. I can't imagine more than 10-15 HP and Torque for mine,
plus some mods I did. I seriously doubt that this is the case but who
knows.

5. This one was just out of anger. Man you are a PITA. But then again an
attitude like yours can bring out the worst in people. Once again
you don't understand, 5200 RPM, Oh.. I forgot sorry.

6. Thanks for calling me 13. I guess a safe assumption would be that you
haven't seen me before. So I guess before you start announcing that
you can read peoples minds maybe you should think about how dumb
you are acting.

You know what's really funny? The fact that I would defend Dr. Dyno even after he shit on me he still doesn't hold a grudge against me. After what you said doesn't seem like much but you did insult his methods. He may forgive you, heck I may even forgive you for that but knowing hes that much different than you, interested in finding out how I can make a claim such as that. Granted he has his reasons to disbelieve me, I can understand, and one day I might be able to show him personally but I will not tolerate ignorance which you surely have provin. Grow up.

 

[John(XJ)Jeep]

It is my understanding that the later years, not sure of the dates, have larger TB to match the intake... so a spacer would be a waste of $$ for the them. If you bored the stock TB on the older XJ's it should make a difference.
Peace

That's nice to know, I thought they were all the same. No experience with the newer cherokee. The're basically the same arn't they?

 

[Beej]

Wow, your still angry at me?

I don't think Max is angry at you, he just doesn't suffer fools well...

 

[DCB]

That's nice to know, I thought they were all the same. No experience with the newer cherokee. The're basically the same arn't they?

They changed a number of things over the years. Intake, exhaust, TB and I am sure a few others. There are many more knowledgeable here that can tell us more.
Thanks

 

[Dr. Dyno]

You measured the small gain with a stop watch? The stop watch determined that it was in the low/medium RPM range?

Yes. I did several timed acceleration runs over 20mph increments at various speeds in 3rd, 4th, and 5th gears on the same road and in similar weather conditions before and after installing my Poweraid TB spacer. I took three times for each 20mph increment and averaged them out. This whole process took me several days as I was obsessive about the results being as accurate as possible. Without access to a dyno, this was the next best thing.
After computing all the results and extrapolating the rear wheel HP/torque gain, the outcome was an average 3-5lbft gain between ~1000-3500rpm and a 2-3lbft gain from ~3500 to redline. That's too small to be felt by the SOTP but at least it's a realistic and honest gain.
It's nowhere near the gains that Hesco claim for their spacer, and even less than the 20hp gain that's claimed for the Helix Power Tower.

The "maximum" 75% VE figure comes from where?

A simulation on Dyno 2000 using all of the 4.0 engine specs. The 4.0 isn't exactly a volumetrically efficient engine in stock form and that's why it responds very well to performance mods.

 

[5-90]

I'll go along with the Dyno2K numbers - that's about all I see using a stock 2686 head using a couple sets of flow numbers.

The big problem with the 4.0 is that the cylinder head doesn't breathe well - again, especially the 2686. The later heads breathe better, with the 7120 being about the best.

I'd like to see two or three flowbench numbers on the new aluminum head - just for other projects.

Before I started really thinking about using a TB spacer - I'd work on opening up the cylinder head and intake manifold.

Also, if you bore out the throttle body, the bore in the intake manifold is the same size. That's still going to leave you hitting your head on intake port flow - fix that first.

The later heads flow better because the runner port angle was reduced slightly - but a crossflow head would be much better. Or, if I were doing a "clean sheet" buildup, I could keep the manifolds on the same side - but I'd go with a slightly taller casting, and raise the intake manifold a couple inches and smooth out the intake runner. The additional separation would also be good for reducing inlet port temperatures.

But why stop there? Go all-out and have either a true Hemi head, or open the chamber up a little and have Diesel-style direct injection (which would eliminate the restriction on fuel injector placement in the inlet manifold.)

The new HESCO/Patriot head (which, I'm suspecting, is cast by Indy Heads - and I'd really like to know, since I took the results of about three months' head-shedding to him a few years ago...) has promise, and I'd consider it a damn good start. Since it's using OEMR parts, it's likely to enjoy a decent market (especially if a complement aluminum block comes out...) but I'm waiting to see what can really happen if someone has a little fun with the design. That someone may, someday, be me...

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[John(XJ)Jeep]

Yes. I did several timed acceleration runs over 20mph increments at various speeds in 3rd, 4th, and 5th gears on the same road and in similar weather conditions before and after installing my Poweraid TB spacer. I took three times for each 20mph increment and averaged them out. This whole process took me several days as I was obsessive about the results being as accurate as possible. Without access to a dyno, this was the next best thing.
After computing all the results and extrapolating the rear wheel HP/torque gain, the outcome was an average 3-5lbft gain between ~1000-3500rpm and a 2-3lbft gain from ~3500 to redline. That's too small to be felt by the SOTP but at least it's a realistic and honest gain.
It's nowhere near the gains that Hesco claim for their spacer, and even less than the 20hp gain that's claimed for the Helix Power Tower.

A simulation on Dyno 2000 using all of the 4.0 engine specs. The 4.0 isn't exactly a volumetrically efficient engine in stock form and that's why it responds very well to performance mods.

That's pretty nifty, was that over a certain amount of distance too or is that negligable? Did you ever try Desktop Dyno? Unless that's the same program you used.

 

[MaXJohnson]

Yes. I did several timed acceleration runs over 20mph increments at various speeds in 3rd, 4th, and 5th gears on the same road and in similar weather conditions before and after installing my Poweraid TB spacer. I took three times for each 20mph increment and averaged them out. This whole process took me several days as I was obsessive about the results being as accurate as possible. Without access to a dyno, this was the next best thing.
After computing all the results and extrapolating the rear wheel HP/torque gain, the outcome was an average 3-5lbft gain between ~1000-3500rpm and a 2-3lbft gain from ~3500 to redline. That's too small to be felt by the SOTP but at least it's a realistic and honest gain.
It's nowhere near the gains that Hesco claim for their spacer, and even less than the 20hp gain that's claimed for the Helix Power Tower.



A simulation on Dyno 2000 using all of the 4.0 engine specs. The 4.0 isn't exactly a volumetrically efficient engine in stock form and that's why it responds very well to performance mods.

Thanks for the info. I've seen enough of your posts and website to guess that you spend considerable time trying to get to bottom of all this. I had thought you probably had been using a G-tech for most of your power and acceleration tech. In any case, I believe you strive for as much accuracy as possible.

I'm a communications engineer by trade and find that most of the methods and troubleshooting procedures used in my trade translate well to other engineering disiplines. When handed a problem to solve, I always start by reviewing what I know, tossing out what others tell me and starting over to determine what I really know. The results of an experiment are only as good as the methods. That's why I brought up the Hesco dyno results. As mentioned, if their spacer adds horsepower, they have the means to provide a very convincing argument to buy one; yet they don't. A printout of some baseline runs (multiple/average) on a truly stock 4.0 and comparison runs (multiple/average) along with a description of the conditions and procedures used. Pretty much what you just described. Instead, we get a questionable printout with little in the way of supporting text. Maybe the true testing isn't coming up with the results they want to see.

Just for fun, I timed the second hand on my garage clock with a stop watch. Over ten 15 second runs, my average error was about 1% with a worse case of a little over 3%. Let's say I clock my Jeep in the quarter mile ten times each before and after adding a throttle body spacer that is expected to provide a 5% gain. With an average error of 1% and a potential error of 3%, I don't like the confidence level of the outcome. What I need is a method of measuring that provides a better level of resolution. On the contrary, if I narrow the 15 second run down to the few seconds it takes to accelerate from 1000 RPM to 3500 RPM, my margin of error quadruples. Throw in some of the other potential error factors and things get worse. Did the weather change during the testing? Air temp, humidity, wind speed? Did I makes all runs with the engine up to temp? Any change in tire pressure? etc.

I believe you did the testing as described and came up with the specified results. Knowing the conditions and methods used, I can determine how much consideration to give those results. As for the 75% VE, it is my understanding that most modern engines(within the last few decades) achieve ~80% VE or better. Knowing your figure is based on Dyno2000, I realize the results are based on an educated guess on some of the imput parameters.

 

[Dr. Dyno]

That's pretty nifty, was that over a certain amount of distance too or is that negligable? Did you ever try Desktop Dyno? Unless that's the same program you used.

I used the same long flat stretch of highway and did timed runs in both directions to eliminate the effect of the wind. Bear in mind that the 2-3rwhp/3-5rwtq gain that I'm claiming for the spacer is within the margin of error of a real engine or chassis dyno so it's too small to be considered statistically significant. I do think that Hesco's 11hp/14lbft claim is outrageously high though.
I have the Dyno 2000 software and I also have some pretty accurate 4.0 engine specs to input so the predicted HP/TQ is very close to reality. I think it's fair to assume that the resultant 75% VE figure using the same software is also very close to reality. With a few external bolt-on performance mods, cam and ported head, the VE of the 4.0 can be raised to 85-90%.
Dyno 2000 cannot model the TB spacer but there's other software (Performance Trends) that can mimic it by inputting a 1" longer intake manifold runner length.

 

[atx xj]

oy John (xj) Jeep....im callin u out man.

Lets see some tape of u peggin 240 in 4th...sounds like BS to me. I dont give a crap about the dozen whitlesses who u say saw u do it. they werent inside the jeep with you, i have no way of talking to them, and no way of trusting them even if i did. borrow a camcorder or something and post it up man. im sure Maxjohnson wudnt mind seein either. none of us would. i also wudnt mind seein u "blip the gas" and hit 4000 rpm's. Hows about u give us the spec's on ur "special built show model"...thatd be a good start that even a simpleton such as urself oughta be able to do

 

[John(XJ)Jeep]

So you have all the 4.0 specs, do you think I can get those off of you. I think I might try out Dyno 2000 see what I can do with it.

 

[5-90]

http://autos.groups.yahoo.com/group/JeepPower/files/

DynoData.zip. Have fun!

5-90