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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
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| Posts: | 214 |
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Posted: Monday December 10th, 2007 05:38 pm |
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DaveShreeve wrote: I'd generally agree with hb, however, rolling roads are also very useful for checking what you're doing; presuming the operator doesn't mod the road, and even then they usually have a good idea what correction factors to apply between old and new. You still have to make allowance for atmospheric conditions but if you've got a starting point before you start modding you can at least see you're personal gains. I'd agree, they're good as a relative indicator. So if you RR'd your car before and after a cam change for example, it will give you an indication to how much of an improvement the new cam has made. Although the actual figures you get might not actually be true figures for your car, though as you say they will be acurate relative to each modification.
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Graham Bichard
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Posted: Tuesday January 8th, 2008 07:49 am |
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mpiman, do you have more details on the airbox mod, as fitted to the JCG kits? Is it possible to replicate this at home?
I know from my years on bikes mods to the airbox can produce very effective results.
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mpiman
Member
| Joined: | Monday January 23rd, 2006 |
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| Posts: | 5 |
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Posted: Sunday January 20th, 2008 07:39 pm |
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Graham
Sorry not to have replied sooner, the JCG airbox was basically the same as standard but with all restrictions within the airbox removed. Mine was modified by grinding away all the restrictions and making a better seal between the airbox and the throttle body. I did not do the work but I know it toook quite a while to do, I do not think that in isolation the mod will make any noticeable difference in performance.
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Graham Bichard
Member
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Posted: Sunday January 20th, 2008 08:31 pm |
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mpiman, I don't suppose you've got a picture of the inside of the airbox do you? (Strange question I know - as if everyone has a picture of the inside of their airbox....).
The reason I ask is, I'm busy reading Vizard's Tuning the A Series book and he describes the airboxes being a big restriction. I've tried the K&N 57i kit and the filter with that is too loud for me (on the long journeys). He also descibes drilling holes around the edge of airbox (on the side AWAY from the passenger compartment). And as for creating a better seal between the throttle body and the airbox, I can only think this is to create some sort of ram-air effect (I'm familiar with this from years on bikes).
So what I'm really trying to find out is, can I get an increase in airflow by modifying the air box (removing the restrictions you mention, holes in the forward edge of the airbox, bigger tube entering the airbox?) to gain a couple of horsepower.
While I'm thinking about it, how would fitting a 52mm throttle body effect the airflow. Yes it has a greater capacity to flow, but would it reduce any ramair effect? And what form of inlet manifold does the MPi have?
Questions, questions, questions..........Anybody got any answers?
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Sunday January 20th, 2008 08:50 pm |
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mpiman wrote: Graham
Sorry not to have replied sooner, the JCG airbox was basically the same as standard but with all restrictions within the airbox removed. Mine was modified by grinding away all the restrictions and making a better seal between the airbox and the throttle body. I did not do the work but I know it toook quite a while to do, I do not think that in isolation the mod will make any noticeable difference in performance.
It also had a small alloy section fitted around the the throttle body aperture to act as a kind of ram pipe to smooth the flow of air further. Also the intake pipe was replaced with a larger diameter square section S works branded item.
I'd agree though it probably wont make a vast difference on its own. A cheap upgrade to the air filter would be to remove the existing intake pip and fit a peice of duct down to the grille to draw in cold air.
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hawaiianblue
Member
| Joined: | Saturday June 2nd, 2007 |
| Location: | |
| Posts: | 214 |
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Posted: Sunday January 20th, 2008 08:52 pm |
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And what form of inlet manifold does the MPi have?
an alloy one...
not really sure what else to say about it. the JC kit has the insides polished out.
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