Advantages of raised top?

Kit Sullivan

Registered User
Clearly, the raised tops to the SCs are more air-flow friendly, but how much of that potential is used without other modifications?
With only a cat-less and free-flowing exhaust as modifications, is there a real advantage to the raised top?
And if so, what are the biggest gains? Top-end power, or low-end torque?
 
There has been testing showing gains when they all came out..Different manufacturers varied. There is also claims of it doing nothing.

Now from a performance standpoint just looing at it you can tell its a POS..

HOWEVER...You will get more from your money at this point from doing lets say..An exhaust/blower pulley
 
I know of an SC owner that had his 94 five speed dyno'd at the same place before and after the installation of a 3/4" raised top and it only picked up 5 HP which could have come from one dyno session too another even with no changes to the car. The other mods to the car at the time were an aftermarket exhaust system and 3.27 gears.They are WAY overrated IMHO, especially on a stock or near stock SC. Once you start to get some serious air flow, (heads,cam, better blower) I believe the benefits of a raised top should show much better results than 5 HP but I have no proof of that.
 
Last edited:
Jimmy..Potentially the car could have made less HP being it was hot.

5rwhp isnt bad though..I do recall seeing claims of 15 crank hp if I recall correctly..I personally never tested it
 
people say it improves throttle response too. weather that is true or not idk.

It doesn't...I was suprised to see 5rwhp gain...I ran better ET with stock one than with a 3/4 raised one. Shouldn't it be the other way?:eek: :eek: Invest your maney in something else - like a UD set.
 
i say unless your runninf 10% over driven and a s port or mpiii dont bother its not a real hp getter but its goood on a modified sc. best bang for the buck exh and over drive pully on blower .
 
Yah pulleyes make a huge difference..Underdrives and a 5% jackshaft..My opinion...ALong with exhaust of course;O)
 
I GOT CLAIMS OF 2/10 BETTER ET WITH OTHER MODS:confused: DONE BEFORE ADDING 3/4 TOP AND UP TO 7 MORE HP:eek:

I've also seen claims of 12 hp gains...but none of the claims I have ever seen have been verified.

Bottom line is that there are so many better places to spend money on go-fast parts than the raised top. Especially when someone is starting to mod their car. The raised top is definitely not the place to start.

With the M90 pressurizing the entire intake system, a raised top is of little value. For a system that blows through the top (i.e. cetrifigual supercharger) instead of pressurizing it, the benefit would be much greater. But since our superchargers are positive displacement, the raised top is really not for anything more than show.

There have been a host of parts listed that will give you better bang for the buck for performance parts. I suggest going with some parts that are listed here already. You will be much happier than the performance you will (not) get from a raised top.
 
I've also seen claims of 12 hp gains...but none of the claims I have ever seen have been verified.

Bottom line is that there are so many better places to spend money on go-fast parts than the raised top. Especially when someone is starting to mod their car. The raised top is definitely not the place to start.

With the M90 pressurizing the entire intake system, a raised top is of little value. For a system that blows through the top (i.e. cetrifigual supercharger) instead of pressurizing it, the benefit would be much greater. But since our superchargers are positive displacement, the raised top is really not for anything more than show.

There have been a host of parts listed that will give you better bang for the buck for performance parts. I suggest going with some parts that are listed here already. You will be much happier than the performance you will (not) get from a raised top.


the raised top does make hp and increases flow but only on well modified blowers. stock top is a restriction on overdriven blowers ....it in itself makes no hp but in a system of high flow parts its integral no one component is going to make big hp .

ported blower with out the other mods like raised top, bigger inlet ,
bigger TB , maf, ic unit, is not going to be a big deal ,

same with steigmire heads probably spelled wrong> but heads with out good exh is a waste you need to improve all areas of air flow .

so to benefit from any part you must have the partner parts ,

a good SC has all the high flow stuff to perform at its best , aka

big maf ,,inlet tube,, TB unit,, inlet plenum,, ported blower,, of any configuration S port D port , MP III, or A/R ,, good IC,, bigger return plenum ,,and matching lower ,, raised roof?????, ported heads ,, exh headers,, free flowing exh pipes,

also a cam change is needed to really get it moving, rockers , etc.

but any of this without the others is not going to make a big difference,

its a complete system from air filter to exh tip at rear of car
 
Last edited:
the raised top does make hp and increases flow but only on well modified blowers. stock top is a restriction on overdriven blowers ....it in itself makes no hp but in a system of high flow parts its integral no one component is going to make big hp .

Please, Manny, show us. I have seen highly modified SCs switch from a raised top to not with no difference in dyno/performance.

If you want to talk about the "system," then there's no point in putting on a raised top unless something is done about the intake plenum. I agree that you need to address the intake as a system. It is also wise to know which parts of the system do more for performance than others. I will say it again...the top is not the place to start modifying your car unless you have money that's burning a whole in your pocket. There are MANY other places to spend money that WILL show an increase in performance.

Just by what Kit wrote initially in this thread tells me that he does not have a modified SC...Therefore a raised top at this point in his modification process is not worth the money...period. I would only do a raised top when all other performance modifications are complete. Then IF there's anything to gain, it will be realized. I'm not convinced it is though, just based on the way an M90 operates.
 
as i said earlier the raised top is for the very well modified SC Ive seen no power increase on none race Sc's

the best areas for bang for the buck on a SC is first exhaust aka ported exh manifolds or headers free flowing exh,
then intake side
of blower aka CAI, TB maf ,over drive pulley , ported blowers intake plenum's,

then maybe go to ported heads but if you have heads off port em ,

yes i know what you mean everyone seems to get a raised top first , its not a needed part at first

on a stocker i say work on intake side CAI is a good point to start, so is exh once exh is done you are ready to mod other things .

like i said the top makes a difference only on very modified Sc's

i sell em but always ask why they feel they need it .

my SC with ported d shaped blower 10% over drive ported heads good exh ported exh manifolds 30 lbs injectors stock maf with center post cut out and sample tube drilled to 15/32 and a bbk 70mm TB ported stock intake plenum

just these easy things went high 13s
ask supercoupe007 of so Calif i took him for a ride .
with stock 270s in rear and my 92 5 spd I get 35-40 feet of rubber into second gear gets sideways sometimes.

i currently have a stock top on my SC and noticed little if any change.

I'm not pluging the tops for the stock to mild Sc's

in fact most of the parts i make wont do a thing for the stock Sc's no snake oil here ill tell ya the truth .

http://rides.webshots.com/album/44127527Torgbo
 
Last edited:
Back
Top