25mm manifold and 12mm plenum spacer

[DevilDRake]

Hey guys,


I was wondering, How much difference would this make as in Dyno results, or take off (with roller rockers 1.98:1) ? My car i'll be getting will be dead stock, and with all of this + it being a manual and maybe 3.7-3.9 gears, would it be very quick changes also?

AND will it fit under the engine cover??

 

[chevy_big_block_bro]

Well from experience I can say that you will notice a fair mid range gain with the rockers. Its not diff snapping power but its noticeable. As for the manifold spacer, Its bolted down to the top of the plenum so it will rise with the spacer if its the 12mm one but I cant speak for the 25mm one. IMO i'd take the engine cover off and polish the plenum lid.

The longer runner length with the spacer did gain a little torque but your main benefit is the cooler plenum and therefor cooler intake air. I had a twin TB manifold on at the time when I fitted the spacer but there was still a small noticeable gain.

The best mod you could do to the V6 is the diff gears. That will show the most results when it comes to takeoff

 

[DevilDRake]

Yeah i know about the diff gears, I've got a list of Dif gears + manifold 25mm + 12mm spacer + throttle body + 1.98:1 rockers.

I just wanted to know if they'd fit under a engine cover as i'm a p plater.

 

[old mate]

yep, will fit under the engine cover.

 

[MACE]

Hey guys,

I was wondering, How much difference would this make as in Dyno results, or take off (with roller rockers 1.98:1) ? My car i'll be getting will be dead stock, and with all of this + it being a manual and maybe 3.7-3.9 gears, would it be very quick changes also?

AND will it fit under the engine cover??

Hey DevilDRake,

In regards to your questions/statements…

“I was wondering, How much difference would this make as in Dyno results, or take off (with roller rockers 1.98:1)?”
The spacers won’t improve a great deal top end (couple of kws) where they really shine is down low, by they I mean they can improve low end torque by around 15% which is definitely noticeably on the road and track.

“My car i'll be getting will be dead stock, and with all of this + it being a manual and maybe 3.7-3.9 gears, would it be very quick changes also?”
Given it’s a manual the shortest I would probably go would be a 3.7:1 gear ratio.

AND will it fit under the engine cover??
You best bet would be to take a couple of measurements just to make sure as every car is different; fitment summary from experience for your car is as shown below.

• Raising manifold by 12mm: Cover will go on like factory
  
• Raising manifold by 25mm: Cover will need to be trimmed around the alternator or bonnet liner needs to be removed or trimmed. Otherwise cover will rub on bonnet liner
  
• Raising manifold by 37mm: Cover will need to be trimmed around the alternator and other parts along with the bonnet liner needing to be removed. Otherwise cover will rub on bonnet liner/possibly not close depending engine mounts
  
• Raising manifold by 50mm: No hope of keeping cover without some serious bonnet mods. Will still require bonnet mods without cover

Hope this helps

Cheers
Steve

 

[DevilDRake]

Thanks alot for that Steve

 

[MR_VX]

would it have any effect if the motor is supercharged ??????

 

[TI3VOM]

The longer runner length with the spacer did gain a little torque but your main benefit is the cooler plenum and therefor cooler intake air. I had a twin TB manifold on at the time when I fitted the spacer but there was still a small noticeable gain.

It sounds like you have it around the wrong way the longer runner length is what made the difference not the insulating properties of the manifold. The air in an engine never sits there long enough to heat up.

 

[habs420]

i got the 25mm plenum the other day, very noticable in the low end!

 

[DevilDRake]

You're talking the spacer yeah?