Post by Driftpimp on Mar 26, 2005 21:12:14 GMT 10
After pulling one of these nuggets apart i found out a few interesting things... apart from it being an inherently inefficient engine.
I just had a few ideas for getting the most out of them:
The intake manifold is bolted directly to the exhaust manifold and the intake "charge" if you could call it that gets very hot once the engine is warmed up... if anyone knows how to weld, it may be a good idea to make a modified header so that its not thermally coupled to the intake. The stock exhaust manifold is a very poor 4-2-1 configuration. (actually 2 runners, but first few inches are separated within each runner)
The other thing is the exhaust gas recycling... block this shizzle off - carby might need a slight tune afterwards
The breather pipe for the crank case is routed back to a plate that sits under the carby. Oil vapour will kill what little power this thing has as well as cause pinging. The best thing to do here is to block it off totally on the carby side and use a small air filter to ventilate the crank back to the atmosphere... this should stop pinging in a lot of cases. Do not block the breather on the top of the motor otherwise you could cause probs.
The mechanical fan also causes loss of response. its not that noticeable but on a motor like this every kw counts. Replace with a thermo fan...
The air cleaner on this thing is also fairly restrictive. Running a twin nostril air cleaner may give you a bit more pull in the upper rev range.
The cheap way around it is to make an extra inlet on the stock can. Cut another breather with a metal cutting hole saw and use a decent grade silicon to glue some 2"-2.25" (whatever will fit) flexible hose into it, and rout it down behind the headlights on both sides.... (Replace the stock breather in the same way)
Just some ideas
I just had a few ideas for getting the most out of them:
The intake manifold is bolted directly to the exhaust manifold and the intake "charge" if you could call it that gets very hot once the engine is warmed up... if anyone knows how to weld, it may be a good idea to make a modified header so that its not thermally coupled to the intake. The stock exhaust manifold is a very poor 4-2-1 configuration. (actually 2 runners, but first few inches are separated within each runner)
The other thing is the exhaust gas recycling... block this shizzle off - carby might need a slight tune afterwards
The breather pipe for the crank case is routed back to a plate that sits under the carby. Oil vapour will kill what little power this thing has as well as cause pinging. The best thing to do here is to block it off totally on the carby side and use a small air filter to ventilate the crank back to the atmosphere... this should stop pinging in a lot of cases. Do not block the breather on the top of the motor otherwise you could cause probs.
The mechanical fan also causes loss of response. its not that noticeable but on a motor like this every kw counts. Replace with a thermo fan...
The air cleaner on this thing is also fairly restrictive. Running a twin nostril air cleaner may give you a bit more pull in the upper rev range.
The cheap way around it is to make an extra inlet on the stock can. Cut another breather with a metal cutting hole saw and use a decent grade silicon to glue some 2"-2.25" (whatever will fit) flexible hose into it, and rout it down behind the headlights on both sides.... (Replace the stock breather in the same way)
Just some ideas
wow, ziggy you actually bothered to write up a mods section for a 4ac, i think this might be a world 1st. On a serious note though, no doubt this could come in handy for a couple of ppl i know... Respect to you for putting the effort in to create such a tech doc. Evan, these mods, and my 2-way.. seriously id love to see ur 4ac drifting better then most of the other guys down at the drift days....
