Plenum gasket question..

[Vette73]

Figured I would throw this question up here before going to my mechanic Tommorow...

Getting plenum and housings ported to 36mm...Dropped an email to Jerrys gaskets stating this....Just got the order in....There's two very thin plenum gaskets in the set I ordered...

Do I need another set? I notice there's two thick gaskets and on either side there are very thin gaskets matching up to the ones I received in the order..

Does anyone follow? The gaskets that I took out on each side of the engine are pretty thick maybe 1/8 inch in thickness...On each side of that gasket are two very thin gaskets ......So do I need another set?

Never took a plenum off a car before just valve covers on a SBC.....

Thanks....

[efnfast]

So, you are saying you found gaskets stacked on top of each other? There should just be a single gasket between the plenum and the I.H. Like what Jerry sent.

[Vette73]

So, you are saying you found gaskets stacked on top of each other? There should just be a single gasket between the plenum and the I.H. Like what Jerry sent.

Yes.....

On either side of the thick gasket there are two very thin gaskets ( one on each side)...I already dropped Jerry an email so I'm guessing he will see it Tommorow..
When I get the parts back from Pete I guess I will have a better understanding of where everything goes...Now that they are not on the car I may be confusing it with something else...

So for the plenum the car only requires one set?

[efnfast]

Uh huh, to the best of my knowledge. Not only that, if it needed more than one, Jerry would have sent you more than one.

[Paul Workman]

Is it a thick gasket, or one of those insulating spacers that used to be so popular to keep the plenum cool? That's my guess.

[Vette73]

Is it a thick gasket, or one of those insulating spacers that used to be so popular to keep the plenum cool? That's my guess.

It is a thick gasket that came off the car....On each side is I think what you mentioned Paul,an insulating spacer....

Jerry sent me two gaskets that are the same as the Insulating ones attached to the thick gasket.......

I know the plenum has been taken off before I owned it....New injectors coil packs and wires.....

[Bob Eyres]

I have those phenolic plenum spacers on my engine. If they aren't causing clearance problems with your intake scraping your hood you can leave them on. But be sure to port match them to the new dimensions of your plenum and injector housings after they've been ported.

[Vette73]

I have those phenolic plenum spacers on my engine. If they aren't causing clearance problems with your intake scraping your hood you can leave them on. But be sure to port match them to the new dimensions of your plenum and injector housings after they've been ported.

I did speak to Pete about this, he is doing my porting....
If I choose to use them again they will probably need to be opened up a bit but they are pretty thick...

Don't know which tool I can use to have it perfectly done...I hear they keep some of the heat away from the plenum but it's not necessary to use them..

[Bob Eyres]

Like with a number of bolt-on mods, such as these spacers, and the "forced air" bumper intake from the same manufacturer, it seems "logical" that they would improve performance. But documentation on the claims is rather thin.
There was one comparison test for a Corvette mag in the nineties that showed about a 1/10 of a second improvement in qtr. mile times. But I wouldn't trust that, too many variables.

[XfireZ51]

I am skeptical the spacers are worth the bother in a motor used for cruising.

[Paul Workman]

I did speak to Pete about this, he is doing my porting....
If I choose to use them again they will probably need to be opened up a bit but they are pretty thick...

Don't know which tool I can use to have it perfectly done...I hear they keep some of the heat away from the plenum but it's not necessary to use them..

I agree w/ Pete and Bob Eyres - snake-oil, far as a performance bolt-on adder goes, especially if the TB (throttle body) coolant has not been bypassed.

The difference between plenum temp with or w/o the Throttle Body coolant being bypassed is significant: only needing the palm of your had to verify that.

So, if keeping the precious DIS module cooler is the goal, there is merit to that. But, as far as a performance adder, At (or near) WOT there's very little time for heat to transfer to the air streaming through the plenum runners. What's more, the stream then also passes through the IHs and the heads which makes up approx 2/3 of the total runner length; both of which are heated by direct contact with coolant!

Taken as a whole, the risk of having a coolant leak or air leak as result of a gap between the (now) three "gaskets" separating the plenum from the IHs (to me) far out weighs any small contribution using the spacer might add to bypassing the TB. And, I agree that "0.1 second" in a drag race ET falls well within the margin of error accumulation by other factors.

That's just my opinion, and shared by others too. But, aside from risk of coolant or air leaks, or interference with the hood, I don't see that using them will harm anything either. So, if Pete still has your hardware, I'm sure he wouldn't mind slapping the spacers onto the (respective) IHs and zipping the die grinder around to match them. Or, with a Dremel you could easily do it yourself at home, I recon.

Is someone (Pete or Marc or ...) going to supply a chip (calibration) to accommodate the added air flow?

[Vette73]

I agree w/ Pete and Bob Eyres - snake-oil, far as a performance bolt-on adder goes, especially if the TB (throttle body) coolant has not been bypassed.

The difference between plenum temp with or w/o the Throttle Body coolant being bypassed is significant: only needing the palm of your had to verify that.

So, if keeping the precious DIS module cooler is the goal, there is merit to that. But, as far as a performance adder, At (or near) WOT there's very little time for heat to transfer to the air streaming through the plenum runners. What's more, the stream then also passes through the IHs and the heads which makes up approx 2/3 of the total runner length; both of which are heated by direct contact with coolant!

Taken as a whole, the risk of having a coolant leak or air leak as result of a gap between the (now) three "gaskets" separating the plenum from the IHs (to me) far out weighs any small contribution using the spacer might add to bypassing the TB. And, I agree that "0.1 second" in a drag race ET falls well within the margin of error accumulation by other factors.

That's just my opinion, and shared by others too. But, aside from risk of coolant or air leaks, or interference with the hood, I don't see that using them will harm anything either. So, if Pete still has your hardware, I'm sure he wouldn't mind slapping the spacers onto the (respective) IHs and zipping the die grinder around to match them. Or, with a Dremel you could easily do it yourself at home, I recon.

Is someone (Pete or Marc or ...) going to supply a chip (calibration) to accommodate the added air flow?


Yes...
Already got the chip back from Mark with the upgrade on it..

Pete did say if I wanted to keep the spacers I could send them to him and
If possible open them up to match the added air flow..

Are these spacers a common add on most members use?

[Vette73]

I agree w/ Pete and Bob Eyres - snake-oil, far as a performance bolt-on adder goes, especially if the TB (throttle body) coolant has not been bypassed.

The difference between plenum temp with or w/o the Throttle Body coolant being bypassed is significant: only needing the palm of your had to verify that.

So, if keeping the precious DIS module cooler is the goal, there is merit to that. But, as far as a performance adder, At (or near) WOT there's very little time for heat to transfer to the air streaming through the plenum runners. What's more, the stream then also passes through the IHs and the heads which makes up approx 2/3 of the total runner length; both of which are heated by direct contact with coolant!

Taken as a whole, the risk of having a coolant leak or air leak as result of a gap between the (now) three "gaskets" separating the plenum from the IHs (to me) far out weighs any small contribution using the spacer might add to bypassing the TB. And, I agree that "0.1 second" in a drag race ET falls well within the margin of error accumulation by other factors.

That's just my opinion, and shared by others too. But, aside from risk of coolant or air leaks, or interference with the hood, I don't see that using them will harm anything either. So, if Pete still has your hardware, I'm sure he wouldn't mind slapping the spacers onto the (respective) IHs and zipping the die grinder around to match them. Or, with a Dremel you could easily do it yourself at home, I recon.

Is someone (Pete or Marc or ...) going to supply a chip (calibration) to accommodate the added air flow?

Hi Paul...

Plenum going on Tommorow ,after I figured out my no start issues...

The gaskets I got from Jerrys are for porting up to 37mm so I am fine with them.....As far as the spacer ( which came on the car ) they look like they match up pretty well with the gasket....

I showed them to a mechanic friend and he said they matched up good to the gaskets......He explained to me that they usually run a little big anyway..

Didn't send them out to Pete to double check, I mean I could have but just never bothered.......Question-Should they fit exactly the same size as the gasket? I mean if they are off just slightly around some of the edges will it make a difference?

To my eye they seem to match up..

Thnx John...

[Paul Workman]

Hi Paul...

Plenum going on Tommorow ,after I figured out my no start issues...

The gaskets I got from Jerrys are for porting up to 37mm so I am fine with them.....As far as the spacer ( which came on the car ) they look like they match up pretty well with the gasket....

I showed them to a mechanic friend and he said they matched up good to the gaskets......He explained to me that they usually run a little big anyway..

Didn't send them out to Pete to double check, I mean I could have but just never bothered.......Question-Should they fit exactly the same size as the gasket? I mean if they are off just slightly around some of the edges will it make a difference?

To my eye they seem to match up..

Thnx John...

Ideally, the transitions are smoth; especially no ridges or pertrusions. But, some "core shift" is common on LT5s. So, there may be some alignment issues of the gaskets and the tunners once assembled. It often takes a trial fitting or two and a little trimming to get it right.