top speed intake manifold for 300hp?

[slow s13]

With these cheaper greddy copy intake manifold hitting ebay and other places what are your thoughts on getting one on a car with 300-350 hp range.

[compression]

The greddy style manifold will not add any horsepower. Because it has short runners, your torque curve will be moved more toward the top end. Nissan wanted long runners to move the torque curve to the lower rpm's.So you basically give up low end torque for more delivery in the top end with the greddy manifold. basically you just move your power around, but dont add any.

[Dori Dori]

Plus full race cut one open and found the casting to be really crappy...the surface was far from smooth like the Greddy unit. Considering it's not much cheaper, I would just buy the Greddy if you really want an intake mani. Like compression said, you'll sacrifice your low end.

[ItzGenX]

I used a dremel to clean out my top speed manifold. I got mine for 290 shipped off ebay. The finish inside was very ROUGH just to let some who don't know.

[Movingviolation240]

Scott from Secret Services called the full race "junk" so I think nuff said.

It's pretty rough compaired to the Greddy one, I'd put it in the same catagory as the infamous OBX turbo manifold. Don't do it for only 300-350hp, you will not pick up anything.

Paul

[chillmieste]

So if intake manifolds put your low end more to the high end but not give you any more power, whats the point of getting one?

[RobDET]

Actuially moving the same torque curve higher in the RPM range will give you more HP. It's just a calculated number after all. But they are right it's not really a big gain for the SR and definately wouldn't be worth it if it actuially hinders air flow.

IMHO the best part of the SR is the flat torque curve.

[S13 King]

who else makes an intake manifold for the SR20DET?

[RobDET]

Greddy/Trust, and Topspeed are all i know of. I'm sure there are MANY more in japan.

[VitaminT]

http://www.store.yahoo.com/pha....html

[SRdave240]

Wow, and a bargain at only $1200!

Looks nice though. At least they tell you what it flows compared to stock.

[RobDET]

those stacks are REALLY nice.

[VitaminT]

Yeah, but for $1200 I think I would modify a GTiR ITB mani to work.

[Def]

Seems to me that the GReddy intake mani. and copies would be more than enough for even the highest powered SR's we're seeing.

The head flow capacity will be the limiting factor after a slightly higher flowing intake manifold is fitted.

[compression]

"The head flow capacity will be the limiting factor after a slightly higher flowing intake manifold is fitted"

Actually the heads flow pretty damn good. When I had my headwork done, the shop had spent days on another SR head trying all sorts of porting techniques and nothing really got them considerable gains on the flow bench on the intake side. They could not really much improve the intake side. THey reshaped the bowls a little and called it good. On the exhaust side, there was room for improvement, and that side got the full CNC porting job.

Personally i dont think that the stock intake manifold is a limiting factor. It has nice long runners for an improved low end, which small displacement turbo engines need. Inside, the casting is very nice, large radii everywhere and smooth transitons. Until I see independent flow tests comparing aftermarket manifolds to stock, I am going to save my $450 for something else. Also, who needs short runners? Top-end power is what the turbo is for!

[Dori Dori]

Actually the heads flow pretty damn good. When I had my headwork done, the shop had spent days on another SR head trying all sorts of porting techniques and nothing really got them considerable gains on the flow bench on the intake side.

I've actaully heard that before.

[Def]

I've seen some flow bench numbers for an SR head somewhere, and while it was very good on the intake side, it's surprising a good porter couldn't gain much. I can understand at high valve lift, but low lift is where you need to improve flow anyway and it seems like you should be able to get some gains with dilligence. I've only seen pics of an SR head though, never actually held one in my hands, so I don't know all this for sure as pics can be decieving.

As a point of curiosity, what was the ratio of intake to exhaust flow on a stock SR20DET head if you've got access to that information?

I agree on the stock manifold being pretty good from the looks of it. I think most of these replacement manifolds are designed for VERY modified cars that are running higher revs and high boost, but people are putting them on rather stock cars and probably losing more overall than they are really gaining up top since their small turbos are the limiting factor.

My comment about the head being the limiting factor was more that once you go with a shorter runner intake manifold with a very large plenum and cross-sectional area, you've gotten 90-95% of the flow gains to be had from improving the manifold. After that you can start getting really crazy with velocity stacks and custom plenums and super large throttle bodies, but you are probably going to start killing the low end power just for a few extra CFM of flow and some more power right before the rev limiter stops the party. The head isn't really a big "restriction", it actually flows very well as you said. It's just that whatever flows through the manifold also has to flow through the head, so one can only get so dilligent about improving manifold flow before you run into that "wall" where the head won't really flow anymore - which is still plenty for 99.9% of SR owners. It's more of a "you've improved that component all you really can given other stock components" rather than a "it's not enough" situation. I guess I should have been clearer.

[TruboostPerformance]

The Greddy copies work just the same, they are copies for a reason. I have installed two of them and the hp gain was very noticable. I bought two to test.