intake spacer

[3100gagt]

what do you guys think about making a 1,1/2 inch intake spacer between the UIM and LIM. Having a machine shop make it pit of one pieca aluminum.

my car has headers,exhaust, intake

[Bjornboy81]

1.5"? make sure your hood will still close. I think theoretically increasing the plenum volume will help with high end torque, but I'm not sure.

[Tebore]

I don't think the hood will close.

It should give you more power just like those intake manifold that are like 5 inches.

I'm interested in seeing results for this.

[TA^Guy]

Originally posted by Bjornboy81
1.5"? make sure your hood will still close. I think theoretically increasing the plenum volume will help with high end torque, but I'm not sure.
That is absolutely correct. Longer intake runners (more volume) creat more torque. A popular modification on the L98 (TPI) engines is to incress the runners for more torque, and the short seamese <sp> were popular for high rpm hp.

For example compairing the L98 5.7 engine making 245hp and 345ft/lbs to the LT1 5.7 engine with much much shorter runners to it's 275hp and 320ft/lbs.

As mentioned we come into the hood clearence problem. TO messure this place several chunks of modling clay on the intake manifold (when cold obviously), fully close the hood, then open and messure the thickness of the clay. For even more accurate messurements, start the car breifly after closing the hood and rev the motor a couple times, this will show the engine movement and space needed.

Another thing would be a throttle body spacer, however I think someone already make it.

[matts]

i think its an interesting concept, and if it fits i think you'd notice a difference

[Bjornboy81]

Thanks for the info John :) I've heard that the TB spacer really doesn't do anything.

Hell if it works, I'd be willing to buy a set. :D

[Sweet98GA]

yeah i didn't really notice much on the spacer i got a couple years ago... i mean yeah i got a 2.4, but it should have done something (according to what they claimed)... i also never put it on a dyno so any increase was not documented

[matts]

i think they're up in the air with most people. the spiral ones are supposed to help HP and the straight ones (like a spacer) are supposed to help torque

[TA^Guy]

Originally posted by Bjornboy81
Thanks for the info John :) I've heard that the TB spacer really doesn't do anything.

Hell if it works, I'd be willing to buy a set. :D
Main reason is that a 1" spacer doesn't really add all that much more volume. The Spacer is only adding 1"x (whatever the diameter is) of more volume to the plenium. Now add that 1" to the runners and you'll get about 2 ro 3 to times as much volume. Anyone with a TIG welder could always fabricate a custom intake maniold with whatever length runners or plenium they wish.

[3100gagt]

Well i tested the clearance with a wax coated paper cup upside down on the manifold and there was 1 3/4 inch of space, now i figured i would have to extend the TB coolant lines and make 2 S brackets for the coil packs to keep them in the original position.

The one guy at work told me to remember 52,52 and that under 5252RPM you rely on TQ and after 5252 your motor turns over to HP to pulls the rest of the way.
Now our cars spend a lot of time under 5252 but im not shure what the car will drop under in a 1st to 2nd gear pull with a PCM. when it shifts at 6K.

I am geting a PCM soon so i will see. I also have headers so i have already gave up the battle for TQ and turned to HP.

[Bjornboy81]

5252 rpms??? Uh, no. He's thinking of the constant in the torque to HP equation:

HP = (RPM's x Torque)/5252

Every engine has a different torque curve, so a set rpm value isn't true...it's different for every engine :)

[Dave C]

I know that some runners are made to a specified length to take advantage of a pressure shockwave. If I remember correctly: there is a pulsing made from opening/closing the valves. If you make the runners the correct length so that the pulse runs up them, bounces and runs back down at the correct time, then the pulses will force more air into the cylinder when the valves are open. For example, some of the old Ford Lightning engines have longer intake runners to increase higher end HP.

As mentioned by TA Guy, you could tune these runners to different lengths to give benefits at different RPM (HP vs. Torque). I think this is because the valves would be opening at different rates at different RPM, making the time needed for the pulse to run up and bounce back different.

Low RPM = longer time between valve opening/closings = longer time needed for the pulse to run up and back = longer runners = more air in at lower RPM = more low end torque

I'm not sure if 100% of what I said is true... I know that there is some kind of pulse created and you can tune the runners to different RPM by the length, whereas I inferred everything else from that info.

[matts]

:lol: there's not a whole lot of cars on the road that go very far over 5300 RPM. i dont know of any street cars, off the top of my head, that will spend any kind of extended period above it either.

[Tebore]

Just some cool info I found out and I figured you guys might like to know.

The new 3500 and the new 3900 have variable length intake runners. A computer moves viens inside the UIM that changed the length of the runners allowing the engine to he excellent low end torque, top end HP and fuel efficiency.

I recently drove a 3.5 G6 and boy is it peppy and feels as light on it's feet as the pre 99 GAs.

[Azrael]

Originally posted by Tebore
The new 3500 and the new 3900 have variable length intake runners. A computer moves viens inside the UIM that changed the length of the runners allowing the engine to he excellent low end torque, top end HP and fuel efficiency. It's only the 3900 that has it. The 3500 upper is a no-runner, all plenum design.

[Tebore]

Really? I thought the VVT 3500 had it too.

[Bjornboy81]

The 3.9 is VVT. The 3500 is the 3400 but bigger....nothing special :)

Avalible engines (http://www.goldkey.ca/gm/new.asp)

[Azrael]

He's not wrong. There's a VVT version of the 3500. I think there's 3 versions of the 3500 in total now. But none had the variable intake plenum to my knowledge.

[Tebore]

^^ Phew so I wasn't dreaming I was reading right. I was reading at 60degree and I might have gotten the 3900 and 3500 mixed up on the variable length runner.

They are swaping in the 3500 top ends into their engines.

Taking the 3100 above 260hp range NA would be nice as soon as the pioneers get the bugs worked out.

[TA^Guy]

Originally posted by Bjornboy81
5252 rpms??? Uh, no. He's thinking of the constant in the torque to HP equation:

HP = (RPM's x Torque)/5252

Every engine has a different torque curve, so a set rpm value isn't true...it's different for every engine :)
Absolutely correct.
Originally posted by Dave C
I know that some runners are made to a specified length to take advantage of a pressure shockwave. If I remember correctly: there is a pulsing made from opening/closing the valves. If you make the runners the correct length so that the pulse runs up them, bounces and runs back down at the correct time, then the pulses will force more air into the cylinder when the valves are open. For example, some of the old Ford Lightning engines have longer intake runners to increase higher end HP.

As mentioned by TA Guy, you could tune these runners to different lengths to give benefits at different RPM (HP vs. Torque). I think this is because the valves would be opening at different rates at different RPM, making the time needed for the pulse to run up and bounce back different.

Low RPM = longer time between valve opening/closings = longer time needed for the pulse to run up and back = longer runners = more air in at lower RPM = more low end torque

I'm not sure if 100% of what I said is true... I know that there is some kind of pulse created and you can tune the runners to different RPM by the length, whereas I inferred everything else from that info.
Dave your thinking of a 'tuned intake', IIRC the Fuel Injected 5.0 Mustang motors had a tuned intake manifold.

[Tebore]

This is interesting.

http://60degreev6.com/discussion/viewtopic.php?t=7745&highlight=plenum+spacers

[TA^Guy]

Very cool. I forgot the UIM is bolt vertically to the LIM, I was going to start wondering about angles if say they sealed at a 30degree angle like the LIM bolts to the heads.

[Prospeeder]

Originally posted by matts
:lol: there's not a whole lot of cars on the road that go very far over 5300 RPM. i dont know of any street cars, off the top of my head, that will spend any kind of extended period above it either.

3.4 DOHC redlines at 7200 RPMs (in Grand Prixs, Luminas, and Olds cutlass), 3.5 DOHC in the intriges also do, 2.3 quad DOHC has a pretty high RPM, most of the DOHC nissans are up above 7k i think for redline, same with honduhs, and what not are in the 7k range or very close. Most 2 Valve per cylinder engines dont usually run after 6k, lol, my car shifts at 5400 rpms i think, it hits rev limiter at 5900 i think, i havent tested it for limiter, lol, and grand ams are what 6200 for redline and 5700 for shift? somthing like that, i havent drivin my moms car for awhile. But its not totally uncommon for cars to have 7k redlines

Iv herd of the whole spacers thing, 60*V6 says its BS
http://60degreev6.com/discussion/kb.php?mode=article&k=19

[Tebore]

^^ TB spacers are BS.

Intake spacers is what's being discussed.

[Prospeeder]

OH! I must have mistaken that for a TB spacer, whoops, intake kinda threw me off, i thought of TB for some reason, I guess UIM spacer is another name for it then, well never mind what i said

[TA^Guy]

As in that thread I have already stated this a few posts back...
but the TB spacer isn't going to have any effect on this because its volume is minimal.

[matts]

Originally posted by Prospeeder
3.4 DOHC redlines at 7200 RPMs (in Grand Prixs, Luminas, and Olds cutlass), 3.5 DOHC in the intriges also do, 2.3 quad DOHC has a pretty high RPM, most of the DOHC nissans are up above 7k i think for redline, same with honduhs, and what not are in the 7k range or very close. Most 2 Valve per cylinder engines dont usually run after 6k, lol, my car shifts at 5400 rpms i think, it hits rev limiter at 5900 i think, i havent tested it for limiter, lol, and grand ams are what 6200 for redline and 5700 for shift? somthing like that, i havent drivin my moms car for awhile. But its not totally uncommon for cars to have 7k redlines

Iv herd of the whole spacers thing, 60*V6 says its BS
http://60degreev6.com/discussion/kb.php?mode=article&k=19


ok, but how much time do they spend about 5300 rpm? not much when you graph it out, a few seconds at a time :)

[Prospeeder]

ah fair enough, unnless there in 3rd gear, im guessing theyd be in that range for a bit, the 3.4 DOHC makes most of its power at the 6k range, i definatly know my car spends very little time at 5300 rpms, seeing as it shifts about right there, ha

[TA^Guy]

Originally posted by matts
ok, but how much time do they spend about 5300 rpm? not much when you graph it out, a few seconds at a time :) I know it's not the same, but even on my motorcycle with a 14,000+ rpm redline and making most it's power at about 12,000 under normal driving conditions I still tend to shift between 5000 and 6000 rpms.

[matts]

exactly. and that's roughly 3 times under the redline. which if you're just cruising around that's where the average car will shift if driving easy. if your car redlines at 7000, that's about 2000 rpm. about right :)

[Dave C]

Originally posted by TA^Guy
Dave your thinking of a 'tuned intake', IIRC the Fuel Injected 5.0 Mustang motors had a tuned intake manifold.


Thanks for clearing that up :D