Prelude SIR Fusion Turbo Conversion


Official MSC Trader
<p style="text-align: justify;">So a couple of weeks ago we had a JDM Prelude SIR come in for a turbo conversion. This car is owned by Simon, a good friend of Mine. In fact Simon has been here before with his old infamous Primera P11GT which we turbo'ed a few years ago, but sadly met its demise a few months later into a wall....</p>
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<p style="text-align: justify;">Anyway!! This car had already been here back in March when we fitted an E-manage blue to it just to see if we could get anything more from it. As it happens we gained a little as it arrived with just 186 HP:</p>
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<p style="text-align: justify;">It had even been here further back still when we did a auto to manual conversion and fitted a custom Fusion light weight flywheel whilst we were at it, so here we were again, this time with the intention to throw in a turbo, mix it with some air and fuel, add a bit of Fusion spice and hopefully end up with a bit of power and a whole lot more torque.</p>
<p style="text-align: justify;">Now the H22A engines are a DOHC 16 valve engine with Honda variable valve timing etc. They are known as somewhat fragile when forcing air into them by means of supercharger or turbo. So the intention here was not to produce record 1/4 mile busting power. After all if we did that it would probably end up in a wall again... (sorry Si).</p>
<p style="text-align: justify;">So the car arrived on a Monday, we first stripped the front end down and took a good look. The system we were to fit was a second hand one that I was told came from an Accord. Apparently everything would/should fit and it was just a case of making a downpipe... Easy except there was no space and oh it had an external wastegate too..</p>
<p style="text-align: justify;">Still undeterred the build went on:</p>
<p style="text-align: center;"><img src="" border="0" /><br />A pic showing part of myself (Ed) pretending to do something useful.</p>
<p style="text-align: justify;">6 days later and the car was complete. Amazingly it started first time with no leaks or problems anywhere. Which was nice since this build included removing and drilling the sump for the oil return, oil feeds and the rest.</p>
<p style="text-align: justify;">So then we went back to the dyno.</p>
<p style="text-align: center;"><img src="" border="0" /><br />This pic was actually from the first mapping session back in the year, but since the car looked the same ignoring alloys, I'm sure it will do.</p>
<p style="text-align: center;">Now for the results.</p>
<p style="text-align: justify;">The car was mapped with the e-manage blue controlling 440cc DSM injectors. Boost was actuator pressure which turned out to be about 5psi. The exhaust was stock 2inch? With a pretty poor 'Chav' back box previously welded on with a near 90deg right angle at the back of the car (nasty) and the CAT was also still fitted.</p>
<p style="text-align: center;">PLEASE NOTE the power on the top right hand graph is that of the old run, you need to read the scale for the now turbo one.</p>
<p style="text-align: center;"><img src="" border="0" /><br />Power VS boost. About 0.37 bar (5.5psi) peak falling to about 0.33bar (4.8psi).<br />Pink is old NON turbo power, GREEN is TURBO.</p>
<p style="text-align: justify;">As you can see from the graph above immense amounts of mid range power were gained. Peak power was 220HP, compared to 201HP before BUT the big news was at around 4400 rpm power had increased from 120hp to nearer 170hp thats a pretty impressive amount of power for only a bit of boost. About 30hp was the average across the band, the difference it made to the drive of the car was nothing short of amazing as is clearly shown below.</p>
<p style="text-align: center;"><img src="" border="0" /><br />Power Vs Torque. Pink before, Green After.</p>
<p style="text-align: justify;">This is really the heart of what's going on. Torque has increased from 140lb/ft @ 4400 rpm to about 205lb/ft. Thats an increase of 46% torque from just an increase of just 36% manifold pressure. This engine LIKES the turbo! However you can see how the torque falls off at the top end as the pitiful exhaust simply cannot expel the gasses. I believe simon has plans to sort this problem out, and then perhaps we will see greater top end too.</p>
<p style="text-align: justify;">So overall this car is a pretty good example of why even low boost turbo conversions are so worth considering. You could tune all you wanted via N/A methods and never achieve these kind of results. Not only that high RPM's are far more damaging to an engine than that of the load placed on an engine by low pressure turboing. Now simon has found that there is no need to give the car death to make it move. He has more power now at 5600 rpm than he ever had before at 7200!</p>
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<p style="text-align: right;">#</p>
<p style="text-align: right;">This article was thrown together by Ed</p>

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