Raised & Stock IC = Good or Bad?

Tim Groth

SCCoA Member
Figured I'd toss this question out since I've always wondered this and just now find the time to post the question. By this point in the game I'm sure its already been asked...Anyhow, everything I write is theoretically speaking so hear me out on this one.

All (most) of us are already well aware of how poorly our stock IC works on a completely stock motor, hence the reason we all add fans, or swap it for double IC's or FMIC's. This is with a stock top that only flows half the air of a raised top aswell.

SO my question is, by increasing the top to flow twice as much air, wouldn't it also double the work load of hot air to the IC...which already knowing can't handle the normal load under stock conditions...so basically the raised top would hurt us more than help us with a stock IC in stock form (no fans etc.).

OR

Does the raised top allow the supercharger to release cooler air since its not having to fight its way out of the compressed area present in stock form? Thus helping the stock IC rather than taking away from it.

Just curious...everyone I ask seems to have a different opinion...imagine ;) .

-Tim
 
If anything the raised top would reduce a restriction causing the air to be cooler...But I seriously doubt it by a marginal difference
 
Does the raised top allow the supercharger to release cooler air since its not having to fight its way out of the compressed area present in stock form? Thus helping the stock IC rather than taking away from it.

The top will present more of a restriction on a different type of supercharger than an Eaton. Say a twin screw supercharger which is actually a compressor. The air is compressed inside the case, then flowing through the rest of the system. Our set-up with the Eaton is not a compressor as it pressurizes the entire intake system from the top all the way to the lower intake manifold.

So, there really isn't an increase in the workload on the IC as such.

The only benefit that I can see a raised top having is simply reducing turbulance in the intake system allowing for a more efficient flow of air...but that is mostly negated by the lower IC tube...

I personally don't subscribe to the theory that a raised top helps out our engines by any significant margine. The only time I can see it helping is when you are attempting to push significantly more air than an M90 is capable of supporting (MPIII for example). Then I can see a benefit of a raised top, but an M90 even to the extent of an MPII does not flow enough air to justify the expense for a raised top.

In other words, until you're running with the top dogs, I think it's snake oil. This is my opinion only since there really has not been any before and after dyno's to support the theory that a raised top increases performance.

If someone has the money to do the independant R&D on a raised top I'll let them prove me wrong. But until then...a raised top doesn't help or hurt us in any way...
 
007_SuperCoupe said:
The top will present more of a restriction on a different type of supercharger than an Eaton. Say a twin screw supercharger which is actually a compressor. The air is compressed inside the case, then flowing through the rest of the system. Our set-up with the Eaton is not a compressor as it pressurizes the entire intake system from the top all the way to the lower intake manifold.

So, there really isn't an increase in the workload on the IC as such.

The only benefit that I can see a raised top having is simply reducing turbulance in the intake system allowing for a more efficient flow of air...but that is mostly negated by the lower IC tube...

I personally don't subscribe to the theory that a raised top helps out our engines by any significant margine. The only time I can see it helping is when you are attempting to push significantly more air than an M90 is capable of supporting (MPIII for example). Then I can see a benefit of a raised top, but an M90 even to the extent of an MPII does not flow enough air to justify the expense for a raised top.

In other words, until you're running with the top dogs, I think it's snake oil. This is my opinion only since there really has not been any before and after dyno's to support the theory that a raised top increases performance.

If someone has the money to do the independant R&D on a raised top I'll let them prove me wrong. But until then...a raised top doesn't help or hurt us in any way...


Well said Sam. I agree 100%. I just don't think that MOST of us are pushing enough air through the stock top for it to be a restriction.

Like Sam, I may be wrong, and others may argue the point, but untill it has been verified one way or the other, I will stand by the theory that the stock top is sufficient for most and will stick with a stock top and spend my money where I feel it will do more good. ;)
 
It was proven that a raised top added about 20 lbs of torque. Theres a thread, but I'm too tired to sort through it all.
 
Tony8470 said:
It was proven that a raised top added about 20 lbs of torque. Theres a thread, but I'm too tired to sort through it all.

Well I did look and can't find anything to support that claim.

Here's the thread that I found the most information contained within:
http://www.sccoa.com/forums/showthread.php?t=12152&highlight=Raised+Top+dyno

Also pay particular attention to this post as well:

XR7 Dave said:
A raised top will not increase airflow. Remember, the blower is POSITIVE displacement. Meaning that the air WILL flow regardless of restriction. About all a raised top will do is lower outlet temperatures and reduce blow-by at the blower. It may also reduce the power required to turn the blower but that is difficult to prove. There are some hella fast SC's with stock outlets. Mine made it's highest RWHP with a stock top on it (313rwhp).

Oh ya, and they are real good at denting hoods. I'd get a raised hood first.

Until it is dyno proven on a stock SC...(with very FEW mods at least) and then dyno tested on a modified SC I won't believe any claims made by manufacturers or distributors. It's all part of the game. Take a look at the HP gains advertised by MP...if you add them all up individually, you'll have a 600 rwhp SC. Only on a highly modified SC will it even remotely be worth considering.

And I think that I'll close this post off with this quote from the same thread referenced above.

XR7 Dave said:
Damon, you analogy is cute, but not really valid. Sure removing restrictions in the path of the SC is going to help, but how? For example, I went from a stock top which read 21psi IN the top itself to a raised top (not ESM's) which resulted in a drop to 14psi within the top. Actual boost at the motor did not change measurably, nor did my 1/4 mile performance.

Very few people understand airflow under boost, and Paul is one of them. However, that being said, it has been proven that there are much better places to spend your money. Ask people on this board how many have created "outies" in their hoods from raised tops. And then ask some of the highest output cars what they use for tops. You may be surprised.

My point was that just because it "looks" like it is better, doesn't mean that there will be an actual performance gain. All I'm saying is that a raised top would NOT be at the top of my mods "wish list."
 
Tony8470 said:
It was proven that a raised top added about 20 lbs of torque. Theres a thread, but I'm too tired to sort through it all.

Well, after you have had a little sleep and are better rested :)p ) maybe you could find this thread you speak of because I sure couldn't find any such claims of proven gains. All I come up with is speculations.
 
I have told many that the raised top is for a well modified SC,
at the boost levels we see on a street car the top flows real good ,

under boost a given area flows around 35-40% better than at a vacuum.

ever notice how we need a 80-90 mm TB and maf to get air flow but blow thru systems can make same power on 70mm .

no secret air flows better under boost its like zipping a file on your computer.
packs all them molecules together we dont use all the air the m90 pushes out thus boost

so a pressurized system is what we have the air sits in a semi stagnant condition until the valve opens its not a constant flow and we do get pulsations within the manifolds .

so a larger area may help to disperse these back pressure waves.

I make many of these parts and try to tell the folks first is exh then heads then over drive blower then blower porting then injectors then a tune.

the top on a stock SC is almost unnoticeable in power gains

stock ic can work to higher hp than many claim it can a front mount with its massive air flow wont add any more efficiencies than a small water to air .
so its not the flow but the cooling that counts. anyway just rambling on .

ill give this post back to its rightfull peoples.
 
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There had bene dyno tests done YEARS ago by various people. And those VARIOUS people had different claims of HP or Torque.

ESM was one of the companies that had tested thier raised top with diffusers and I do recall the torque increase being over 10ftlbs.

Much like everything on our car or any car for that matter a part that removes a restriction will only flow as much as the next closest restriction.

The raised top will only provide an improvement is it is the restricted part of the system.

I will give the straw analogy...Blow air lightly through a mixed drink straw...You may or may not feel a restriction dependant on how hard you blow. Blow harder you most definately will feel a restriction. Now take a regular drinking straw. Blow lightly through it. You may or may not feel a restriction..Blow harder and you will start to feel a restriction....However it will not be nearly as great as what was felt on the smaller mixed drink straw.

There is a point where a raised open top will make a much larger difference. This is all dependant on the amount of boost you make and what other restriction may be in the factory or your particular system.

The same goes for any part on a car.

MAF are a good example. At what HP level do you need a particular MAF size to flow unrestricted a certain amount of air?....Same with a TB..Same with an IC...SC inlet...Even though sucking (TB. MAF, INLET) is different then blowing through (Ic Tubes, IC, Intake) or exhausting (headers, exhaust) there are still restrictions.

Price per HP is always a consideration. I think it is foolish to say headers wont do a thing just as much as I feel its foolish to say a raised top wont do a thing. But when these items become worth the $ per HP is what I still feel is relatively not thought out.

I'll take a raised top and headers anyday....Because our motors are air pumps just like every internal combustion engine known to man...And what works on others will work on ours. Once again..Its the $/hp factor that needs to be looked at. And Dave D and other feel that mods such as these arnt worth the investment..And they may be right...Or they may be crazy..Or they just may be the lunatic your looking for....Good ol Billy Joel.. haha
 
Thanks for all the replies.

The main reason I asked this is for the fact that I've used these tops on all of my SCs and have read the documents Bill posted over on SCP regarding the different makers of tops and how they flow...but never seen any documents to support gains...and well it seems as though if they did exsists they're old and lost or non-exsistant. It's crazy that at this point in the game there is nothing documented on this.

The majority of people I've asked have just given me the, "well it could only help, than hurt ya." response...which yea okay but given me more reason to agree.

Any how, if anyone finds anything more to support a benefit or loss of using one, I would love to read and learn.

-Tim
 
I tend to agree with Sam. One of my first Mods I made for my Sc was a beautiful 1.5" raised top. As far as I can tell I havent seen any indication of increased HP from it but it sure looks nice under the hood. Like most SC owners we tend to make several modifacations at the same time so theres no way to prove which mod was responsable for HP gain from one dyno session to another. I beleive the top is a waste of money untill you have the heads, cam and other mods to make use for it. For me, I have everything in place for the heads and cam to make some serious HP down the road.

Ken
 

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From What I,m Told And Know Is ,

IT WORKS WELL WITH OTHER MODS:eek: OPEN EXHAUST:) 10 % PULLEY:cool: CAM :p UNDERDRIVE PULLEYS DI/C WITH FAN:rolleyes: BIGGER MAF & TB :D ALL THIS WORK TOGETHER WHICH I HAVE ON MY SC I HAVE CLAIMS OF 2/10S OF AN ET FASTER BY THOSE WHO USE THE ONES I MADE I NO LONGER MAKE THEM AS IT,S TO HOT NOW MAYBE COME FALL MAY START AGAIN :confused: JUST MY 2 CENTS:p
 
A raised top will help.But not much ,not until the IC tubes,intercooler
and plenum, lower manifold are opened up and looked at as system.

The key word is SYSTEM.
The top is only one peice in the beginning of the intake or IC system.
You modifi all the parts as a matched system. Blower hat,
IC tubes, intercooler, plenum,lower manifold, port matching.
It is just common sence.

I sometimes think that a lot of people on this board subscribes to the
magizine IGNORANCE IS BLISS .People here are always splitting hairs
when disscusing a part, instead of seeing the hole picture.A system
of parts.

Randy:)
 
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I have a NEWBIE SC question

I always see 3/4 raised tops for sale, in the for sale forums.

Why don't they sell the hole top? What good is just
3/4 of a top?:confused:

RANDY
 
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Well, I've got to agree with Sam, at least at this point. I removed my raised top and I can not tell a noticeable loss performance. In fact, it feels like it might might pull a little harder on take off. So I would say unless there is some dyno proof, you might gain very little horsepower on a slightly modded SC.
 
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