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Post by mikuni on Aug 15, 2012 18:07:26 GMT 12
^ nice post penti. Good to see you're still floating around. And thanks for the general advice on C20XE tuning. I might have to pay Tony a visit for my track car too, lets hope he works on Vectras as well as Chevettes. Be interesting to see how well your throttle bodies work, sounds promising if they work OK on a 2L BEAMs. This is Markku from oldschools engine in his AE86 race car. Standard internally running a Link Storm and making 186bhp at the wheels on a mild tune through silvertop throttles, so they can definitely flow enough for a relatively racey C20XE. It would take a lot of time and money to make a C20XE out flow the throttles. image doesn't work?? click the link to go directly to his great build thread oldschool.co.nz/phpbb/viewtopic.php?f=17&t=14419&start=80
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Post by friendlyfire on Aug 16, 2012 17:41:00 GMT 12
some very nice photos there penti, would love to one day have my chevette out there with all of you! why wait untill 25th december for christmas when you can have it any day of the year? ecu arrived, link g4 storm, with nzefi wiring kit, inlet temp sensor, injector clips lockable aerocatch bonnet clips, because i have removed my bonnet catch, so before hand anyone could of gone into my engine bay! little jaycar kit for interior light delay, keeps interior light going when you get into your car for a set time then fades out like those fancy Mercedes. this little chevette wont know what to do with himself with all this 21st century technology!
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Post by gordo on Aug 16, 2012 22:11:52 GMT 12
i can't see 43mm 'flies being a ninderance until getting quite a bit higher spec' than you're currently going to have - it should be better than a 45, or even a choked down 48, sidedraft as there isn't the choke and venturi sitting in the airflow. What about the fuel flow'pressure rates of the injectors being up to the job? You may want to figure out the best total intake length, though, to match the torque or power peak you expect the engine to provide.
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Post by friendlyfire on Aug 17, 2012 17:06:09 GMT 12
standard injectors will be fine for now, they say theyre ok upto 200hp, will just get my set cleaned and tested, whats a good rpm to have maximum torque at for a street/ track car with the c20xe??
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Post by gordo on Aug 17, 2012 17:31:59 GMT 12
Stock engine has peak torque at 4800rpm and peak power at 6000rpm. However, that's going to be due to the specific intake, exhaust, etc for the stock engine. That said, I'd be using those figures (maybe 6500 for power) when designing them. A mate worked out an induction length for mild cams - all that can be used without deepening the valve notches in the piston - and if I can find out, I'll let you know - I think it was 15" but not sure. I can measure the SBD throttle bodies from the bell mouth to the head, which may be a useful guide.
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Post by friendlyfire on Aug 17, 2012 17:48:37 GMT 12
awesome thank you, that would be very usefull gordo if you could do that, thanks
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Post by pentti on Aug 17, 2012 22:04:12 GMT 12
Hi Guys, Heres a link to a good site which discusses the porous head issue which affects a small proportion of the non-COSCAST c20xe heads. If you are unlucky enough to end up with this problem, it seems it is easily fixed, rather than binning the head. Good photos and description of 2 different methods of fixing it. www.orsas.com/CarStuff/cav/index.phpSome of you may have seen it before.
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Post by mikuni on Aug 18, 2012 11:41:11 GMT 12
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Post by gordo on Aug 18, 2012 16:24:23 GMT 12
That's great, Brad, Jenvey used to have some great info' on their site but it was removed some time back.
The SBD Jnveys are 230-235mm (bit awkward to get to the flange face) from the heat to the bell face.
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Post by gordo on Aug 18, 2012 21:32:28 GMT 12
Found a comment that the XE seems to like a valve to bellmouth opening of 300mm, that would be close to what the jenveys are and a mate made up a plenum with runners of that length for his XE (on Anderson 270 cams - they fit without machining) and the type "C" exhaust manifold with a 2 1/2" exhaust. With the ARP rod bolts (STRONGLY RECOMMENDED, if I haven't already mentioned them), he runs to 7k5 and it's still pulling strongly. If it's still live, this link should show his results on a dyno - they stopped the run early (also did for my car), but should give some idea of the potential - especially the lower rpm torque!
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Post by mikuni on Aug 18, 2012 21:46:40 GMT 12
The 300mm intake appears to lift the torque around the 4750rpm mark, which is nice and low. The C20XE has a brilliant torque curve anyway and lifting the torque earlier will give it good midrange horsepower while it will still make nice peak power as you spin it faster. It's clearly still pulling at 6500, but looks like it might be about to drop off, judging by the torque curve.
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Post by gordo on Aug 18, 2012 21:51:42 GMT 12
Still a slight gai, Brad - found another printout where they used the full rpm potential. . Not that much difference from what you had with the ECOTEC in your Chevette wagon, IIRC?
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Post by mikuni on Aug 18, 2012 23:23:36 GMT 12
I never dyno'd it but Tim did recently. 143hp is 107kw, so yeah almost identical. The above plot is before Chad fitted his ITB's though isn't it? With my throttles I just went as long as possible, which usually works best for most people. Longer should bring the torque down to make more midrange, shorter will move it up making more top end.
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Post by gordo on Aug 19, 2012 0:55:22 GMT 12
It is indeed, and as he feels the torque has been increased throughout the rev' range, he may be a bit higher than that.
A while back I still had the original, run in, engine dyno figures from SBD, but haven't seen them for some years, damnit! it was corrected to 204hp, with stock cam's and, I assume, the SBD dyno manifold and exhaust which would have been a type "C".
i've seen power curve overlays between several different engines and the XE seems to offer quite a bit more midrange than others, even if they loose a bit at the top end.
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Post by friendlyfire on Aug 19, 2012 20:30:44 GMT 12
is there any way to know if i have a coscast head without taking the head off? very good read, thanks brad cheers for all the info, really helps alot, so will be aiming for a intake lengh of 300mm, im guessing it dosnt matter if i go smaller inlet manifold and longer ram tubes or longer inlet manifold smaller ram tubes? just as long as its 300mm total length to the valves? ps. gordo you got to put up some pictures of your car! im keen to see it
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