Thread: Xcessive plenum - which runners?!

Hi guys, I recently completed my ve headswap on to my UK de bottom end, the bottom end was opened up too, so rough spec is as follows:

de block
16ve head and IM
CP 12.5:1 ve pistons
4cw crank
g-spec pulleys
n1 cams
powerland 4-1 header

the car's going well, and although the only figures i have for it are low, the dyno dynamics they're from is reknowned for reading very low compared to say dynojets. It made 173whp or 207fly hp, however my tuners 400hp s13 also read approx 60hp low on this compared to the local Janspeeds dynojet.

I'd guess i'm around 190-200whp on a dynojet, the car feels very good so i'm not looking into this to gain 'lost' power.

AAnnnnyyywaaaayyyyyy, i was thinking i could use some improvements on the intake side of things, and rather than an n1 IM, i was looking at the xcessive bolt on plenum (cash is tight or i'd go for a full on IM). Then using a q45 TB and maybe afm to further aid flow.

Question is if i go for this plenum, which runner length will suit me better, the n1 or stock 16ve runners? Runner length is witchcraft to me so this maybe a stupid, difficult to answer question?!...

I'm revving to 8.5k and currently making near peak power at 7200rpm, holding it all the way to 8.5k

any thoughts or help for an IM n000000b

thanks

Craig

the n1 would be more appropriate but Im almost sure the adapter plate the made is for the sr20ve runners.

How are you making team power at 7200 wih n1 cams? I assume your using cam gears ? With my manifold I went with 7 " runners this put my peak power at 8400-8500 with n1 cams straight up the car holds power to 9400. If you want to keep he same power band you will need longer runners. Don't expect huge gains with a manifold probably like 2+3% increase at most wih good tuning. I went with full custom from them but there cast option is nice since you can keep stock inj .

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ah good point, i was assuming it'd fit the 16ve or n1 runners

mr sentra: yeh i perhaps worded it wrong, i make pretty decent power only say 7hp off peak by 7200, and it gradually climbs towards 8-8.5k and doesn't drop off. I'd like to rev higher and see how long it held for but i've been worried with a 4cw de bottom end/light pulleys i might be puching my luck?

i have arp rod bolts if it helps lol, but rods are stock. s+r also stock 16ve - can i go to 9k or more safely? it won't be held at those kinda revs for long like an all out track car.

and as far as the mani and tb thing then you'd suggest the xcessive plenum might not do much good then and custom the way forward?

i had a play with a few websites that work out (dont know how acurate) your runner length they were saying i would need 8-10" for peak power at a usable 7-8Krpm

what length are 16/20ve runners? roughly that aren't they? with n1s shorter

OK,forget runner length then. do people think it'd be worth trying the excessive plenum and q45 on my stock 16ve runners for any kind of gain?

also, here's my graph - ignore the plateau at 5500rpm, my mss is playing up so both cams are switching together at 6400!! I have a feeling my car actually isn't even reaching peak power til above 8k where this graph cuts off and my stupid jdm speed limiter is kicking in. Long story short my n1s appear to be makin power where you'd expect. Is revving to 9k safe on my 4cw bottom end and stock s+r?

are you measuring 7" from the valve seat or the face of the head?

Face of the head is 7" to top of velocity stack. Stock s&r should be ok to 8.5-9 ish on n1 cams. I use aftermarket springs with stock bottom end. If you want to push power down try 8-9" runners and use cam gears to pull peak power lower . With a proper spec 4-1 header power should peak higher than my 4-2-1 budget header that is ment for peak power at 7-8 k