primary and center section diameters?
Turbo Mini Forums

Hi, im using a 1800 vauxhall block with jenveys.. even with other modification it wont see over 200 bhp, im having a manifold made but what primary and center section diameters should i go for?

1.5" (38mm) or 1 3/4" (44.5mm)

then a 2" or 2.5" center?

cheers Mark

have you got more specs ( the more the better.. stroke/CR/etc etc preferably flow numbers or even better dyno numbers) i could run it through pipemax and see what it spits out. it's pretty accurate most of the time.

4 in one or tri-Y ?

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Thanks

It will be a 4-2-1 manifold

Capacity(cc)-1796
Bore(mm)-80.5
Stroke(mm)-88.2
Compression Ratio- 10.5:1

its not been on a dyno yet - but i estimate about 165bhp and 130lb/ft

I also need valve and stem diameters, cam timing numbers (and rocker or followers ratio if any) and lift.

Peak power RPM's you are shooting for.

I have got it on a different computer so you would have to be patient as it is elsewhere

If you feed it good data it will give a pretty ( to very good) good set of measurements that are hard to improve on (unless you spend a lot of time and effort for the last ounce)

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Intake valve 1.00 - 1.40 mm

Exhaust valve 1.40 - 1.80 mm

Will edit this when I find the rest - cheers

Edited by MarkGTT on 10th Apr, 2014.

those valves are tiny..


i ran the numbers for a 2.0 XE based on the specs that I could find and a 284 kent cam. 5250 to 7750 rpm

This is what it gives:

for a 4 in 1 system

Primairies

1.47 inch diameter.

length either 2 nd harmonic ( best bet) 32.6 to 34.8 inch or 3 rd harm. 22.8 to 25 long


collector: 2.7535 inch diameter ( or nearest i say) starting from end of primairies you could keep overall lenght to either 17 -34-68- or135 inch lenght to end of tailpipe

for a tri-Y

1.59 inch diam. 1st part 16.3 to 17.4 inch long
1.722 inch diam 2nd prt 16.3 17.4 long

collector 2.485 to 2.735 diameter. total lenght as above

Edited by Sir Yun on 14th Apr, 2014.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

my ported 16v 1.6 head joost in case it helps. stock valves ,high vel ports .

http://i32.photobucket.com/albums/d44/ivan...uoise16v008.jpg

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

thanx Robert noice curve.. and quite big flow numbers on the intake.


the lenghts do go down an about 2 inches when you downsize to engine so i do need the exact specs. The short answer for the original question would be 1.5 primaires and 2.5 for the collector.


oh p.s

those lenghts work best if you have a big resonator/wave termination box after the collector so the dampers/mufflers downstream do not affect the tuned lenght. a straight thru glass pack muffler makes the pipe longer from a wave perspective so you need to watch that

Edited by Sir Yun on 14th Apr, 2014.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Thanks yeah clearly the valve size above is wrong.. I blame the cut and paste on the iPhone. :)

Thanks for the info :)