what size exhaust tube/elbow etc for my setup?
 

Ok so my cut'n'shut DET manifolds now finished (see thread http://www.nissansilvia.co.uk/vbb/showthread.php?t=1466 ) so nearly ready to trial fit it to the car ready to make a new elbow, downpipe and exh system. My question is regarding the bore of tube to use. Bit of background on the spec and what its used for may help with your suggestions.
its a CA18ET as in the S12s with Autosprint cam, flowed head, KA t/b, CA20E inlet manifold running 444s, forgies and steel rods, with a turbo technics T28 lo-lag hybrid, all controlled by an Emerald aftremarket ecu. Its used for sprints and hillclimbs, so response is key rather than out and out power but that said dont want to restrict the motor if i wish to up the boost again:p
currently runs 250brake at 16psi but looking to run bit more possibly?....

current system is 63mm (2.5"), will that be enough or do i go 2.75 or 3"?

Ive got a elbow now (cheers Mike:cool: ) thatll be cut up for the flange and the lambda boss.

Hi Craig. I reckon 3 inch but other people that are in the know will advise you better.

Was wondering where you got your 'autosprint' cam from and whats the difference from this one to a piper and standard? In the process of getting a cam so i can finally fit that vernier pulley i purchased off you some time ago.

cheers

Paul

Hiya Gripo:D
cheers for that, thats what im thinking too.

Autosprint cam is a regrind by Autosprint in Coleshill, nr Birmingham. They did all the balancing on my engine and rebore etc. I havent got the specs of the cam, it was all abit a) hush hush b) above my head anyway lol. The guy at Autosprint, Geoff, looked at the silvia engineering cam (i assume Piper) that was in the engine i blew, and worked from there. its deifinitley different to the eye than the Piper and has non-symetrical lobes with a flat on the downside of the lobes. Dunno why, its a trick they used on ford pinto profiles amongst others. A few of the guys that have fitted them since, have noticed the engine bretahes better at the top end of the rev range and stops that slightly strangled feel. Ive never measured the lift or duration etc or done back to back with teh piper, but it works very well in my engine. its a bit more expensive i think than the piper, about £120 iirc. Turbomike has one for sale i believe if you PM him.

personally i would go 3" as you expect to use more boost,you only have half a exhaust to make anyway:D

im actually gonna go all soft in my old age and have the exh sticking out the back again rather than the passenger door:D . It wont have any silencing tho, well not to start with, and then only if the sound police at events get the arse and make me put a silencer on:(

oh yeah did i mention it will have a passenger seat again, and will be road legal (well have tax MOT and insurance anyway:D )

On the road
 

Sounds t like that will be a bit lively on the road i bet lol!!!:D :D

no you didnt:) ,is anybody brave enougth to get in there then:confused: :eek:

http://www.ss1turbo.co.uk/photo.htmfound craigs car on here.

im only gonna fit the spare seat for track days really and it will never be run on the road as it only has a 2 gallon tank.

whats the highest power output of all the simmy boys you know craig?

mines the highest sprinter at a modest 250, but Pete silcocks road and trackday Sabre is knocking on the door of 300+ with his VNT protoype turbo and a DET. Stew B is building a killer DET with big turbo (for a scim anyway) and is looking for 350+.
One of the old Reliant dealers, Graham walker Ltd in Chester, built a Sabre (same as mine underneath but much prettier) that was factroy backed before relaint went bust. It was built nearly 10 years ago and had all one off internals. titanium rockers, Omega forgies, steel rods and a Lumenition ecu. Turbo wise it originally ran Rs500 T4 turbo and Pace intercooler for circuit racing, but they ended up on a T34 hybrid. Ive raced against it and to be honest the power delievry was crap for sprints and hillclimbs but the workmanship was stunning. the cars been sold recently and the engine blown up, so a new one along the lines of mine and yours is being built for this coming season, should be nearly ready by now i reckon.

i was going to mention that one, it was red, i had pics of it, it had a weired tubular manifold, someone told me it was 20ltr, i sold an et engine a couple of years ago craig, it was one of your scimmy crew, he fetched it for a friend, ithink he was from norfolk way.

yeah thats right, it was based on a Ca20 rather than ca18. Ran a bluebird head with rear dizzy and std inlet manifold with cossie TB. odd looking tubular exh manifold was to try and improve power delivery and packaging iirc. The guy that owned it, had someone else build the car. Ive spoken to the owner Graham Walker but hes not really interested in it now as hes sold it, but i would love to find the guy that built it and developed it.Ive loads of pics somewhere i will dig them out. I beleive most of the engine work was done by Oselli Engineering at the time, as there were no real jap tuners around then.
dunno who that was re the engine you sold, but im bound to know them, it aint like theres many people daft enough to play with scimitars!

edit pics of the car are at work, will post some monday

ok mate cheers, i was told the guy who did a lot of work on it and built the manifold was a dentist, no bull, and just alately theres a guy in the jap mags who maps cars and he was a dentist, could this be the same guy:confused: .

yeah thats right, he was a retired dentist!
Barry something or other his name was, i will ask a mate who kenw him for his second name. I think him and Graham actually shared the car when it was circuit raced in the 750MC calsses before they changed.
Barry Marsden, im sure of it, although i will check with my mate to be sure.

,i would of been interested to see the power output with the rs500 t4 on there ,must have been using a LOT of boost,was this car successfull at all

in between melting turbos and blowing engines, yeah it was quick. i think they got a bit disillusioned to be honest, they ran an SS1 like mine but with about 230-240 brake and that was good, but all the time and effort not to mention money that went into the Sabre didnt really pay off. I think it was just a lack of development. There was so many 'urban myths' as to power out put, but some just didnt add up to my mind. Ive heard 400bhp bandided around although around 300-340 with the T34 was the last figures i heard before it was sold. i suspect it was running 280-300 reliably but the T4 turbos and big boost were killing engines and parts left right and centre. Not a problem when a car dealership and factory was backing the car i suppose.
It was finally retired about 6-7 years ago and has passed thru a couple of owners since, before being sold to a current sprinter who blew it up testing it a month after buying it! a new modern spec engien should see it more reliable and quicker tho.
The only track i have data from that ive raced at and it did, my car was quicker ound the lap although slower max speed over the start/finish line. Rumours of when it ran full slicks and big boost, it ran 1.5 secs quicker than my best time so ive got summat to beat i suppose ;-)

sounds a very interesting car,would be interested to see pics of car/engine posted up ;)

no worries, will do monday mate

yeah craig, i was tol 340/400 bhp, i did have pics of it, the guy who bought the engine sent me some on my old pc, it had graham walker on it in big block letters.

back to the original question, 2.5 inch should be big enough for 300bhp, the difference in size from 2.5 inch to 3 inch will change how and where you get the power really

Thats the one! i have soem techie pics and half a dozen of the engien bay i will post tomorrow.

Danny
for packaging reasons 2.5 would suit me better, can you elaborate on the differences in delivery? also any idea on the differnce in noise levels between the two as we have to meet static noise tests at every vent and drive by at some too. i was trying to get away without running a silencer you see, altho the exh will be longer than i cuurently use as it wille xit out of the rear of the car

going for a slightly smaller bore should give you a little better off boost response . The 2.5 inch system on Lou's s12 has a single silencer and is seriously loud, probably louder than a blitz NUR. I doubt you'll pass scrutineering without any silencers, you'll probably need a cherrybomb style middle box and a sensible backbox at the very least

i currently have a 2.5" system with a single Jetex medium length oval silencer which exits thru rear of passenger door. That runs static at tested rpm 4350(suppossedly 2/3rds of max ;) ) at between 98 and 102Dbs. variance is generally how up to temp engine is and how good the testing equipment is. Ironically although it registers apprx 100Db static, its quieter on track than some of the mildly modified V6s that register 89-96Db. The turbo does a great job of chopping up the sound pulses when under load. Im gonna lag the system from manifold all the way to tail pipe which will help a bit (and stop cooking me!)
Whaddya reckon?

I thought most tracks made you be under 96db now?, lagging should help, the tubular manifold will make it quite a bit louder. I'd run that Jetex box in the middle and a 3 inch tail pipe silencer personally. If you make it from Mild steel it will be a nicer sound too

no sprint hillclimb regs are 105Dbs except where thats over ruled by the venue, but i can only really think of Castle Combe which is 102. Think its summat to do with the fact most venues have planning permission for so many days a year at higher levels, but all the other dates such as track days etc come under normal planning noise restrictions.
Thanks for the suggestions re exh. I was gonna use mild due to it being a bit lighter and bit more ductile than SS. should as you say, take the crackle of the exh note too.