Keri-WMS Posted December 16, 2009 Share Posted December 16, 2009 This is off-topic really being a non-Starlet engine...but I bet it's pretty close?Basically I blew up my AW11's 4AGE and thought "I'll just clean up a spare head and do a simple 1.8ish coversion using the 7AFE block". As normal I got carried away, I thought "may as well go big valve to help the extra 200cc's worth of charge" etc and it went from there!The old 4AGE head, I think I can see what was wrong!The standard bigport 4AGE inlets:Modifying the inlets:Going big-valve, note the change in the gap between standard valves and new valves!Nice new oversize wasted-stem valves:Finished chambers, de-shrouded the valves, opened up ports, 4-angle seats (inlet):Finished inlets, valve guide and boss removed! (maybe a bit extreme...!):Old vs recon/modded!Exhaust manifold de-dingleberried then flowed 1mm oversize radially to improve the anti-reversion/standing wave formation step (head flowed to match gasket, manifold is bigger:Covers cleaned, painted in high-temp matt black then draw-filed by hand:Not shown are inlet manifold and TVIS port-matched, exhaust valve gaps to be run way oversize to increase valve speed off seat (increasing wave/pulse formation and pressure at the expense of a tiny bit of lift and duration), cams to be re-timed by drilling/slotting the pulleys (over and above mods needed to get in line with the 7AFE bottom end), and other bits and bobs.POWER ---------------------------------------------------Well, using very basic crazymaffs:128bhp plus cone filter and straight through exhaust = maybe 135bhp?Assuming 135bhp, 135 / 1.587 (1587cc) = 85.07bhp/L.85.07 x 1.762 (1762cc) = 149.9bhp.In terms of added poke, there could be a 5-15% gain in power from the ruthless flowing, call that 5% = 149.9 x 1.05 = 157.4bhpThen the valve area has gone up by 10.1% and 16.5%, looking like this:29.5mm dia Toyota small port in = 683mm area (94% of the bigport valve)30.5mm dia Toyota Bigport in = 730mm area Bigport25.5mm dia Toyota ex = 510mm area Bigport32.0mm dia Atlantic in = 804mm area (110.1% of the bigport valve)27.5mm dia Atlantic ex = 594mm area (116.5% of the bigport valve)In actual fact the EFFECTIVE diamter of the new valves is even more, as I'm running much smaller seat contact areas, making it more like a 20% increase.157.4bhp x 1.2 = 188.8bhpIn reality I'm expecting about 160bhp +/- 10% once set up properly, at 1,000 less RPM, with much more torque due to the longer stroke. The theory from the point of view of air entering the port.1 - Upper port (is this the part you refer to as the "runner"?). Standard, just had casting marks removed to maintain velocity and improve the boundary layer.2 - Valve guide boss. These are there to support/cool the guide, and also in the GE head they appear to induce rotation in the flow over each valve as they are very lopsided (plus the ports are angled in pairs when looked at from above, not parallel!). The outside curve of the port is the highest velocity area as the air tries to keep going in a straight line, so I wanted to know what effect removing them would have (this probably means more revs or more lift needed).3 - Valve guides, these were in the way of removing the guide bosses! Of course I know a cylinder is a pretty good aerodynamic shape so they are not a real problem if retained...4 - The throat, this is the real venturi as it's right behind the valves and is the smallest area (especially now!). All I did to these was remove the "step" caused by mis-alignment between the port and ID of the steel valve seat insert. Doing this opened the seats up to about where I wanted to go due to the bigger valves anyway. I'm keeping the standard cams, and I WAS going to stay at the same capacity to do a fair test of the effects - but decided not to bother and to try the 7A one straight away as I've not got heaps of spare time for multiple engine configurations/comparisons. NOTE: This is me in "hobby mode", I don't pretend to know my way round engines to any real level!!! Quote Link to post Share on other sites
ste91 Posted December 16, 2009 Share Posted December 16, 2009 Would it not have been better to go for a 20v head? Quote Link to post Share on other sites
Keri-WMS Posted December 16, 2009 Author Share Posted December 16, 2009 Would it not have been better to go for a 20v head?Really needs to rev to get the most of the 20v, and the 7A block isn't that great. Plus I wanted it to look standard and be cheeeeeap.Plus I always wanted to have a go at gasflowing! Quote Link to post Share on other sites
riko666 Posted December 16, 2009 Share Posted December 16, 2009 And who can blame you - the work looks entirely professional and you've obviously done the research beforehand. Impressive work Quote Link to post Share on other sites
Keri-WMS Posted December 16, 2009 Author Share Posted December 16, 2009 And who can blame you - the work looks entirely professional and you've obviously done the research beforehand. Impressive workCheers! ;) Quote Link to post Share on other sites
Sparky Posted December 17, 2009 Share Posted December 17, 2009 Looks tidy mate going to do mine one day!! Quote Link to post Share on other sites
chr15_7_t_ Posted December 17, 2009 Share Posted December 17, 2009 how do you go about doing this urself?is it a tricky job or could someone with the right mind and tools do it? Quote Link to post Share on other sites
Keri-WMS Posted December 17, 2009 Author Share Posted December 17, 2009 To "do what I did" (and I probably went too far) you'll need:- An air die grinder, with burrs and a compressor.- A valve seat grinder with stones at the various angles.- About two evenings per port!!!!! (ouch)- Bigger valves, I back-cut mine as well (not shown)Beyond that, you also need (I didn't have):- A couple of spare heads to trash while testing ideas on...- .....the flowbench.- Some real idea of what you're doing (buy books by A . Graham Bell)! :-)Basic things to know are:- "polishing" the ports is a bad idea, it lets fuel condense on the walls and messes with the "boundary layer" (the air right next to the metal, which forms loads of tiny vortexes that "lubricate" the main mass of the air as it moves).- DON'T change the shape of anything (I should really have left the guide bosses in place).- The main gains to be had are by improving the valve seats at low-lift (the more angles of "cuts" there are in the valve rim and it's seat on the head the closer to a smooth curve you have, imprtant at say 1.0mm of lift where the air is trying to get through a tiny slot)! The faster (more like "earlier") the bulk of the charge in the port can start to move the better the resulting final velocities are, creating a better "ram" effect if the inlet runners are tuned properly etc.- The remaining gains normally to be had are "port matching" the inlet side, and removing or smoothing any casting / machining lumps or steps in the inlet/exhaust ports.- DON'T port match the exhaust side....there needs to be a "step" from a small port in the head to a larger manifold branch. This step acts as a anti-reversion device to reduce exhaust gasses going back into the head, and also sets up the pressure waves that you are trying to match when you fit a "tuned" exhaust.- The same pressure waves exist in the inlet runners, but they orininate off the back of the inlet valves.Just to reiterate - aim to get a nice "valve job" and "tidy" the ports/gaskets etc to remove anything that shouldn't be there and you may improve things a bit without causing problems.One other thing, there are differances in n/a engine porting and forced induction porting, like f/i needs big wide cantact areas for the exhaust valves due to the far higher temperatures...they transfer the heat to the head via this small area. The cooler your valves, the less detonation they may cause, and the higher your boost can go!Tuned exhausts are less of a worry on f/i cars as well, as there is not room for a big curving 4-into-2-into-1 manifold as you need to fit the turbo in there...and as close to the engine as possible in terms of distance though the manifold to keep the gasses as hot as possible (heat = pressure).It's all in the details! Quote Link to post Share on other sites
Guest Enzo Posted December 21, 2009 Share Posted December 21, 2009 impressive mate! Quote Link to post Share on other sites
Keri-WMS Posted December 21, 2009 Author Share Posted December 21, 2009 impressive mate!Ta! (we'll see when I get it built and on a dyno ..... ) Quote Link to post Share on other sites
Sparky Posted December 21, 2009 Share Posted December 21, 2009 Be good to see I think I am going to this as a final year project (Motorsport Engineering) seeing as we have a flowbench and I will have a spare head to do it on Quote Link to post Share on other sites
Guest Enzo Posted December 21, 2009 Share Posted December 21, 2009 could anyone post up a pic of what i flow bench looks like? Quote Link to post Share on other sites
Sparky Posted December 21, 2009 Share Posted December 21, 2009 I'll see what I can do now Quote Link to post Share on other sites
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