RotaryRevn

A quick question. I know that the series 5 na intake manifold yields big gains over the series 4 na.

Does the same thing hold true for the series 5 TII manifold over the series 4 TII manifold? I was once told that the series 5 TII manifold had a better torque curve than the series 4. My friend is giving me a series 5 manifold for free. Is it worth swapping out? Also, I can see the differences between the series 5 and 4 upper manifold. Is there a difference in the lower manifolds or do I just need to swap the uppers?

thanks and I did search for all the search *****.

rx7_turbo2

On a T2 you need both upper and lower intake manifolds to make it work.

rotarygod

iTrader: (1)

There is no noticable difference between the two different manifolds. The physical differences are very subtle. You'd be lucky to see any change on a dyno let alone any feelable difference.

RotaryRevn

I got the idea from the Australian forums. Those guys seem to swear by the series 5 turbo mani. I just got the upper portion of the series 5 today. I gotta wait a couple weeks for the bottom, my friend has it stored in Arkansas. Anyways, side by side I do see a very noticable difference in the two. The series 5 runners are much longer than the series 4. They go up quite a bit higher, then down farther making them much longer than the series 4 (mind you this is only the upper, I don't have the lower yet). I noticed it as soon as I got them side by side on my garage floor. I couldn't really tell the difference just looking at them while on an engine in the engine bay (other than the runners raising up as you near the rear of the bay (almost like stairs, and the dent on the series 5). Maybe I will post some pics up of them side by side once I get the lower portion of the manifold. I would think that the longer runners would produce a better torque curve. It's true, probably not a big enough difference to invest in buying one but hey, it's free so I might as well try it. Maybe while I'm getting my engine tuned on the dyno for my Microtech, I will have them dyno it with the series 4 and 5 and see if there is any change in the powerband.

Thanks for the input guys!

rx7_turbo2

The S5 runners are longer and larger in diameter. I personaly think that there is an advantage to using them.

jreynish

iTrader: (2)

I agree with rx-7 turbo 2
there is a noticable difference it is both longer and wider in diamter allowing for more flow.. since it is forced induction the more flow the better!

RotaryRevn

Yeah, it is wider, I can't wait to try it out

Rotorific

iTrader: (1)

the best improvement is the FD intake manis

RotaryRevn

Is there a good source for FD intake manis? How much do they run and I would need the throttle body too right? Does the FD mani bolt right up?

thanks

BLUE TII

iTrader: (9)

I got the idea from the Australian forums. Those guys seem to swear by the series 5 turbo mani.

I have this feeling that they were refering to the S5 turbo EXHAUST manifold VS the S4 turbo exhaust manifold, but I could be wrong...

There is no noticable difference between the two different manifolds. The physical differences are very subtle. You'd be lucky to see any change on a dyno let alone any feelable difference.

Having had a S4 TII lower intake manifold (LIM) beside a J-spec S5 LIM I agree w/ this as far as LIMs are concerned. The S5 2ndary runners were ~1mm larger.

I would believe there are more gains to be realized by backwelding and grinding out the EGR intrusion and porting out the center mounting boss stud where it intrudes into the primary runners.

Not to mention it is easy to hog out/polish the runners by several mm w/ a die grinder w/ 10inch extension shaft split for 80 grit emery cloth while submerging the lower end of the LIM in a bucket of water- so S4 LIM could be easily "enlarged" to S5 specs.

As far as S5 VS S4 TII upper intake manifolds (UIM) I have no clue as I went w/ S6 (3rd gen UIM).

the best improvement is the FD intake manis

I don't understand how that would be the case as the 3rd gen LIM will not fit up and does not incorporate the correct radius runner bend, not to mention the 3rd gen primary runners are MUCH smaller than TII primary and the 2ndary runners are only ~1/2mm larger than S5.

The 3rd gen UIM can be made to fit the S5 LIM w/ some machine work and has a completely different design that incorporates those small diameter, long primary runners and a small inline surge chamber. This should keep off boost velocity high. The very smooth constant diameter 2ndary runners should promote good flow once on boost.

I used 3rd gen UIM, but changed its fuction by hogging out the primaries after their surge chamber and removing the 2ndary throttle butterflies so it is no longer a high velocity low volume system. My set-up boosts before 2,000rpm, so don't care about "off boost"

An added benifit to the 3rd gen UIM is that w/ that same 10inch die grinder extension and bucket of water you can port and polish the full length of primary and 2ndary runners because of its direct design!

Another benifit to the 3rd gen UIM is that the 3rd gen throttle body (TB) is slightly larger than the TII TBs.