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Exhaust Science

Started by motec6.9, 14 October 2012, 06:48 PM

motec6.9

PS i have refitted 300hp NOS system to car  ;D . But once i get to paint the car i will look at putting it back on the road. Geoff PPS Did low 13s at Kwinana Beach Dragway on old motor before NOS lean out  :'(
Euro 6.9 255.6hp at the wheels. Watch this space.

TJ 450

Geoff,

You're not considering NOS on the custom build engine are you? That would be manic!

In any case, those are bloody good figures on the existing engine anyhow. I wonder what it would be like with K-Jet retained, the 560 throttle body, and those extractors?

Do you reckon a stock exhaust mated to your extractors would still perform well in excess of the stock manifolds? That's what I would do if I went down that path with mine. I would want it to sound stock with extra performance bite to it.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

motec6.9

Hi MT Cam replied about 560 throttlebody manifold sold it a while back but and good workshop should be able to do the job for you. Interestingly he is not finished with W116 doing something very rare i will leave it at that as i dont want to steal his thunder for when i am sure he will post about it. Geoff :)
Euro 6.9 255.6hp at the wheels. Watch this space.

motec6.9

Hi Tim my car made 160hp at the rear wheels on gas fitted with impco 300 mixer it was to small intended for motors between 3.5 to 5 litres. Yes i was thinking of leaving NOS on when i put big motor together. For those that dont know my original  motor has had the heads ported and fitted with thinner vavle stems. The block was sonically checked and bored from 4.21 inches to 4.31 inches it was able to go to 4.5 inches.  The crank was sent to Melbourne to Crankshaft rebuilders who made a new billet crank for me . Old crank was 3.74 inches new crank is 4 inches with big block chev journal size. I have a set of Aries forged rods and custom deck height pistons the comp will be 10 to 1 .The parts are currently grease wrapped waiting for funds to recover before motor goes back together still need gasket set. This motor will not be the small 417 cubic inch M-100 you all know it will be 466 cubic  inches. So far i have spent just under 10000 on the big motor with heads and machine work plus pistons rods and crank. Engine builder are saying it will make a lazy 500hp.Now Tim to answer your queastion stock 6.9 make between 160 to 175 hp on dyno. Cams fitted with 560 throttlebody and 2.5 inch duel exhaust  made 190hp at the rear wheels so those 2 mods gave anywhere between 15 to 30 hp increase. My car with same size exhaust and extractors made 215hp at the rear wheels so another 25 hp. But i still had standard 75mm throtlebody on my car at time but with efi fitted. So i would say the extractors would be worth around 20 to 25 hp increase.When the car is getting painted i would like to finish big motor and i will look at getting copys of my extractors if anyone is interested.Geoff :)
Euro 6.9 255.6hp at the wheels. Watch this space.

motec6.9

Hi Tim and MT I hope some of this information is helpful. Geoff :)
Euro 6.9 255.6hp at the wheels. Watch this space.

motec6.9

 :)Hi Tim I was wondering is your car euro spec with 8.8 comp or aus spec 8 to 1 comp ratio . Anyway as I have dunked my car a few times I am aware of were power figure should be . Geoff
Euro 6.9 255.6hp at the wheels. Watch this space.

ziper1221

How does forced induction change exhaust flow? I imagine it would mean that the least amount of flow resistance, the better.

motec6.9

Hi Zipper yes that is the case with turbos most definitely. But only half true with supercharging as it does not make a huge difference if there is a restriction. Geoff  :)
Euro 6.9 255.6hp at the wheels. Watch this space.

TJ 450

Hi Geoff,

The info is great, thanks. The mods certainly make some difference indeed!

I'm not sure what engine I've got to be honest, although I believe it is US spec, so probably low comp.

I'll look into this 560 throttle body mod, as I have one at my disposal. However, removing that intake manifold again will be a real PITA, but I think it would be worth it. 8)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

motec6.9

Hi Tim it was nice to meet up with you if you need to borrow a manifold to measure I have one not on a engine. As for when I am home at the moment how long is a piece of string. Done over 130000km in last 11 days in the air and more to come flying for 20 hours today . Going on what I have seen with dyno and cams car 560 throttlebody is worth around 15 hp at the wheels but a big increase in torque. Geoff  :)
Euro 6.9 255.6hp at the wheels. Watch this space.

oversize

Yeah but what about the bigger 100mm (LS?) one??
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

TJ 450

Indeed Motec, that was quite timely. That's hell of a lot of flying. 8)

I reckon throttle response would be epic off idle too, very easy to spin the wheels I would say.

I'd probably just pull the manifold and go for gold, but I won't be doing it for a while. I'll keep your manifold in mind though, as I'll pull the TB off the spare 560 engine at some stage soon.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500