Allpar Forums banner

1 - 16 of 16 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter #1
Hey guys was curious to see if anyone out there has ever tried using a throttle body spacer on a naturally aspirated 2.2 or 2.5... Fortunately I have a friend who works with a CNC machine on a daily basis, so I gave him an old throttle body a gasket and on his free time at work he made me a 2 inch Throttle Body Spacer for my 2.5 Circle Track Car. I'm thinking with the intake being as short as it is this should give it more veloicty and hopefully give the ol girl a little more take off power coming off the corners.. Any thoughts?? Also here is a pic of the finished spacer.. I have another pic of it but can't get it to load on here.
 

Attachments

·
Super Moderator
Joined
·
21,357 Posts
The results are variable and there are yes and no votes as for spacer advantages all over the internet. I didn't notice any 'seat in the pants' increase in power on my old Horizon carburetted 1.7L under any driving conditions.
I think that a lot of car manufacturer science already goes into intake/exhaust 'breathing/tuning' manifold design and if a spacer made the power differences that some aftermarket companies (Airaid, Vortex, etc.) claim, that the auto makers would be all over it in a heartbeat.
In theory, they might work on some engines with insufficient manifold runner designs, but for the most part I say the claims are just marketing hype.
Certainly if one is made for you, give it a try and let us know if it made a measurable difference.
 

·
Super Moderator
Joined
·
31,983 Posts
It won't do anything except prevent you from closing your hood. You want turbulent air flow downstream from where the fuel is introduced, and this will encourage laminar air flow, which will result in a less even fuel mix and therefore, a little less power.
 

·
Registered
Joined
·
70 Posts
Discussion Starter #4
One thing to keep in mind is this engine isn't your "factory stock" engine. 12.5:1 Compression Ported and Polished Head, Ported Intake and only runs on 110 octane etc, etc.. This engine is built for racing so since the spacer was "free of charge" were gonna give it a try. There is a shop here locally that has a chassis dyno and I've contemplating on putting the car on it for "giggles".. I figured this would be the best way to see if any performance is achieved. I'm looking for some baseline numbers anyhow so hopefully it will help.. And Bob the hood clearance doesn't concern me,that's just a "hood pin adjustment". I'm also looking into to fabricating up a new mounting bracket for a larger air cleaner. This thing sounds like it has a massive vacuum leak when you stand on the throttle but is just the air being sucked in the air cleaner.
 

·
Registered
Joined
·
1,605 Posts
My vote is that the sharp angle bend below the TB will negate any beneficial effects of the spacer. But give it a shot, if it works I'll put one on my car.
 

·
Administrator
Joined
·
29,620 Posts
My thoughts on the spacer are that if you raise it above the floor of the manifold a bit it would aid in the sharp transition between down and to the cylinders. Sure the angle may be as sharp but the fuel will have the chance to atomize just a bit more as it travels farther mixed with the air. The bottom of the TB is a reverse cone. This means that the opening where the butterfly valve (throttle) is smaller than the actual size of the 'bottom' of the TB. So, it seems to me that the air is 'pulled' in all directions at once as it enters the plenum. It seems to me that this 'expansion' helps to pull the molecules (sp?) of fuel further apart as it mixes with the air. So if it can travel just a bit further it 'may' help with that process well before it hits the sharp angle.

If at the bottom of the plenum just below the TB opening the floor of the plenum is 'roughed' up with dimples etc. designed to tumble the air rather than guide it the atomization process will be aided just that much more. The finer the atomization of the fuel with the air the better it will burn, the better it burns the more power and more complete burn will result. This may mean better power and better economy. The distance above the floor is unknown. Two inches may be great for a 12:1 CR engine while 1/2" may be good for a daily driver.
 

·
Registered
Joined
·
246 Posts
Ffstro;

I am not ready to add the turbo system to our Sundance but my machinist is building a custom spacer for theintake to work with the port/polished head, that is going in it sometime this month.

I will let you know how the spacer feels unless yours gets done first. The first thing he told me when he got a look at the TB II intake was that he expects that he can improve the flow A LOT with a spacer! He opened up the exhaust manifold to match the exhaust too. I am gettin g excited as the Sundance is realy feeling different these days.
 

·
Registered
Joined
·
70 Posts
Discussion Starter #8
Hey guys sorry I'm late posting any follow up with my throttle body spacer on my built 2.5L. But anyways, of course i had to replace the factory bolts for longer ones in the rear and for the 2 bolts for the front of the TB spacer I had to use 2 pieces of metric all thread. After installing the spacer I did notice a tremendous difference in the throttle response upon acceleration. There was no hesitation when you went from idle to wide open throttle. Driveability wise the car definitely had a much better throttle response coming off the corners.

Dissapointing part was I didn't get to do much testing with the engine because 8 laps into our feature race I was deliberately wrecked and ended up rolling my car.. Engine is ok for the most part but the car is trashed. I can testify that when you build a race car don't skimp on safety!! The chrome molly cage held up and can and will be used again in our next car. Next project car is a 91 ES we pulled from a junk yard. We will be transferring everything over this winter..
 

·
Registered
Joined
·
1,828 Posts
Sorry to hear that, man... I've always been curious about TB spacers on the TBI, since you're essentially looking at a carburetor with a solenoid valve in it instead of jets. It's been more of a "You want HOW MUCH???" situation for me, and since the response I've gotten on here has been overwhelmingly "probably won't do much", I can't really justify the expense. I wonder if the benefit was more from the spacer allowing the mods to your engine to work better or from the spacer itself, i.e. how well this would do on a stock engine. Did you ever get it on a dyno before it got trashed?
 

·
Registered
Joined
·
70 Posts
Discussion Starter #10
Getting the car on a dyno was one of my main goals. Last fall just 1 mile up the road from my house/shop an import guy moved into a shop and had a chassis dyno. I talked with the guy about putting it on the dyno and doing some testing. He told me he could even go as far as installing a new EPROM in the ECM and reprogramming the ECM via a laptop. But before winter was over he packed up and moved somewhere near Newport News, VA (to my understanding).. Apparently our town didn't like him doing dyno pulls at 2-3am at night! They basically harrassed him enough he just moved out. There are a few chassis dyno's in my area and I still would like to get it on one just to see what kind of numbers it is producing and what kind of powerband it has. I have a friend who has a daily driver with a NA 2.5L and there is no comparison at all between these two engines. I'm usually not a guy who is about numbers but I would love to see what kind of numbers this engine would put up because it is torqy as all get out. I'm more of a "where is our power, how broad is the power band etc, etc.." HP numbers really don't matter to me. To me it's about "what can you do with what you have".
 

·
Registered
Joined
·
70 Posts
Discussion Starter #11
I would post pics of the spacer installed but for some reason when I try to attach the file it keeps saying an error occured and won't attach it. Can anybody help me out or give me an idea of what I'm doing wrong?
 

·
Premium Member
Joined
·
20,074 Posts
One thing I have noticed with the intake manifolds is the pinch of number two and three runners. Thing is, when I modified one, it requires actually removing some of the outside of the runner and refilling it by having a friend tig weld a piece in place, then I epoxied the outside for extra safety and seal, it is a pretty tight spot. YOur piece looks like the TB manifold instead of a 2bbl carb setup, but filling the extra manifold area so the plenum area on the engine side of the plenum is filled, then underside rounded from the stack you have to the two splits to the two cylinders helps flow, too.

12.5 and you have to run 110 octane better be choice, but I could guide you through the proper means to have more power without having to use 110 to do it. Since your head is ported, they only did half the job. Bet they didn't touch the exhaust port at all, one thing they say don't touch because it will mess up the flow, which is not an exhaust porting problem, it is a combustion chamber problem. Are you using the 782 or G head? And most of all, what method did you use to get your 12.5:1 compression? Is it the stock parts common block combo (using 2.2 and 2.5 parts), or domed pistons?
 

·
Registered
Joined
·
70 Posts
Discussion Starter #13
The head is a 782 and has been completely ported and polished Intake and Exhaust side. Can't take anymore material out otherwise your in the water jackets. Intake has been ported to match and the stock exhaust manifold has been ported and polished (we aren't allowed to a aftermarket headers).. As far as gaining the 12.5 Compression Ratio was fairly simple. The 110 octane is not by choice, this engine will not run on straight 93 Octane. The engine is a complete modified and built to race engine only. I'm not going to go into complete detail on the engine builds but I can tell you when it idles people can't believe it's a 4 cylinder, they think it's a small V8.
 

·
Premium Member
Joined
·
20,074 Posts
I understand not being able to tell me everything about the engine, was just wondering if the 12.5 was done with a common block combined with the flat topped pistons of the 2.2 on 2.5 rods with a 2.5 crank. I am not positive of the combination of the 2.2/2.5 components but know it can be done, I lost the article that actually had the info without having domed pistons. I'm gong to drop a 2.5 Dakota into my 63 TR4 and do a compression raise on it, your combustion chamber isn't ported right, I will be, and have, run on 87 octane without any problems with 12.5 (actually 12.7), the 782 head has some combustion chamber flaws that cannot be overcome by simple porting and polishing to the max, work needs to be done to the chambers themselves. If you want to converse other than here, just pm me and I will help you out, do it all the time.
 

·
Registered
Joined
·
1,828 Posts
As for pictures, use photobucket or something like that, that's what I've always had to do.
I would be really interested in getting that non-modified 2.5 on a dyno and then doing pulls with your spacer and without it. That would really put this to rest, and if it makes a difference, your friend with the CNC machine might have a little business...
 

·
Registered
Joined
·
246 Posts
ffstro: My daughter has been driving our 2.5 NA Sundance with the intake riser for the past 3.5 months. It made acceleration much smoother, it is very happy to get up to speed now, its no 2.2 T2 but definitely not a normal NA 2.5 either.

We used 1", wound up clearing the hood without adjustment. Could have gone another 1/4" but that was in contact with the hood, so 1" it was.

-The only thing I can suggest to you is to take a look at the 94+ NA intake manifolds, they have incorporated several torque building modifications. Most of what was changed can be added to the older style manifolds. I have held off on installing the P/P head as I was not completely certain my daughter would perform as a new driver.
 
1 - 16 of 16 Posts
Top