okay, I am in a need of some mods that dont cost that much
so far I have got a AEM cold air intake, $265.00
DC sports race header $360.00, would that be the best way to go for quick and inexpensive preformace mods,
progress rear sway (suspension, $145 on ebay)
twm short shifter and cable bushings ($130 for both)
just ordered the P2R throttle body spacer ($80) and the corsport intake manifold gasket ($50) and will install in the next few weeks.
these are all cheap as hell, and the sway bar and short shifter (with cable bushings) work wonders for me. the car handles terrifically and shifts shorter, crisper, and tighter. i ordered the gasket and TB spacer because they were shown on 8thcivic.com to actually give your car an increase of 3-5 hp to the wheels with both products installed. pretty damn good for the price!
A throttle body spacer doesn't work, they can't do a thing for hp. It's one of those scams that keeps showing up no matter how hard engineers try to persuade people not to waste their money on them.
The Si engine, and most engines today, breathe somewhat differently than carbed engines did. With a carbed engine, a spacer between the carb and the intake manifold actually did work, allowing a larger plenum under the carb for storage of more air, a better vacuum signal to the carb, a better mixing of the gas and air, and that allowed a faster start up to the air flow when the intake valve opened...as well as a straighter shot to the port, but it didn't work in all cases.
The Si engine breathes in gulps thru the throttle body, it takes a bubble of air, then takes another as each intake valve opens up and it does this to fill that large plenum that links the intake passageways. This design permits a faster fill of the combustion chamber and gets the air moving faster as the valve opens up, becuz the cylinder is filling from a reservoir very close to the valve--the plenum--right at the end of the intake passageway. An important thing to remember is that the engine does not fill from outside of the throttle body--it fills from the plenum.
Take a look at the intake manifold. Have you ever wondered why you see the intake passages run right into the plenum at right angles? It seems to contradict everything we know about air flow--like four gently rounded curved intake tubes into each intake valve from the throttlebody--which was the ideal setup for a carb. However, for fuel injection, the present setup works the best and gives far better throttle response.
A spacer does very little, if anything and certainly provides a very modest increase to the total plenum volume--not enough to increase air volume, increase flow or improve hp, becuz the plenum is large enough already.
I suspect that the hp increase that was reported is a manufacturer's estimate or a dyno run made by an overly optimistic tester--it happens a lot. Also, a dyno run made on a cold engine, in this case it would have taken time to install the spacer and the intake and throttle body would have cooled off very quickly while the hood was up and the throttle body removed from the intake. That extra cooling would give the hp increase, but it would quickly drop as the engine warmed up the intake.
If hp were this easy to achieve, Honda would have added that spacer and claimed their target of 200 hp.
Oh man...I can see people yelling at me right now. Moderators please be prepared to step in.....
Japan - can i ask what you do? everytime i'm on here and read a post by you(which are always well written) I always learn something new. Just wondering how you know all this stuff. and with that said how do you feel about the coolant bypass for the 06-07 si throtle body? is it worth it?
I'm a retired Naval Officer and consulting engineer, electronic and mechanical. Have consulted with companies such as GM, Ford, GE and many others, including many of the largest electrical distribution companies in the US on how to improve electrical distribution to stop blackouts, etc. (they didn't listen and the reasons would surprise you, but that is not within the scope of this forum). Although, no longer involved with my company (I'm retired due to an accident)--am still developing patents for electronic cooling packages and making more efficient electric motors and generators.
The throttlebody (TB) bypass option does work, and works very well on certain cars, such as the various V8 powered GM versions. This mod works best on hot, humid days. I believe GM and Ford made a mistake, not by including a TB warming device, but on how it was routed. There is absolutely no need for this device on a hot day. It should have included a temperature sensitive shut off to close it off or reroute the hot coolant away from the TB when the engine was fully warmed up and they didn't do that. They probably saved 25 cents or a little less per car.
I'm not certain about how it works on the newer Civics, because I don't know anything about how coolant is plumbed into the throttlebody--haven't studied it and my manuals are in storage. However, if there is hot coolant circulating within the TB on a hot day, you can bet that bypassing it is going to raise hp. This has been proven for years and it usually is from 3-7 hp, depending upon how hot the day is. It should be re-installed for winter use to prevent icing. Eliminating heat from the intake system of any car on a hot day, not only improves hp, but improves driveability and gas mileage.
One thing Civic owners should be aware of is that Honda has a very complex engine running program within the computer that varies fuel mixture and timing to control the engine operating temperature. As a result, I don't know how much rerouting any hot coolant line away from the TB will affect the operating parameters of the engine, such as where is the IAT (Inlet Air Temp) mounted...before or after the TB? The only thing that can be done is to try it and see what happens, and remembering that an engine will always run better if the entire air intake system is insulated from hot air no matter what the source of that heat is.
If a throttlebody bypass is used, allow about 200 miles of normal driving to allow the computer to modify the "Integrator" and then switch to the long term "Block Learns" for normal running, before doing any dyno work to evaluate how much extra hp has been made.
Sorry for the lack of response to the challenge by Japan! I know i cant convince everyone, especially those engineers out there but i want to post the reasons why i made the TB spacer purchase. See the dyno charts below, read the whole post from those who ran the dynos, and tell me if its not worth $80 bucks?
Nope, the consistency is the problem. Any change to the intake system will initially yield a slightly lean running engine. Slightly lean running engines will make more hp than an engine tuned to run on the road. It will take roughly 250 miles for the computer to retune the engine, in which case it will go back to normal running. A change in size of the plenum, in this case it is larger, will always add hp to the upper end without any change to the lower end, esp if the plenum is too small. Did you notice that the change was fairly consistent over the whole rpm range? That's the problem.
If you do notice a difference, it will likely be very small and that is within the error of the dyno. You should have made at least 5 baseline runs and avged them to obtain the proper hp output, then 5 runs with the TB spacer and avged those as well. Each run should have had a cool down period of about 15 minutes each, then check oil temps in the transmission and engine, then tire pressure and tire temp. Also, the exhaust should have been wired with thermocouples to measure EGT. EGT would show that it was running lean.
When all that is done, put at least 250 miles on the engine then run the tests again first with the TB spacer, then without. Then run the car about 250 miles and run another baseline.
You were running a chassis dyno thru the tires, tires can easily affect a dyno run by at least 5 hp (as they heat up, the pressure is increased and less hp is lost thru tire rotating friction). (For detecting small hp increases such as this, there is only one dyno to use and that is one that is attached to the flywheel.) There was no proper cool down for the engine--it was running hotter and hotter each time which thins the oil in the engine and the transmission and that means less parasitic loss (rings and oil). Heat is hp, esp. if it was running slightly lean. All of this means dyno errors which can easily hit 5 hp, and more.
So, you see, the consistency is the problem. If Honda could see an increase this large with just a simple spacer, they would have added it, or lengthened the plenum. Why not call Honda and tell them what you have discovered and how simply they can add the hp? It would be a great 2008 addition.
just kidding. well japan, i thank you for giving me a $400 lesson on engine mechanics and proper dyno testing to argue over an $80 part. Unless you feel that it will HURT engine performance, i'm going to slap it on and see what happens. the way i figure, it cant hurt, and it was cheap. I'll see if its a noticeable difference between when i first install it and after driving for a while. i guess i'll just have to report back in a few weeks.
oh and those werent my dynos so i cant speak for what they did /did not do. I doubt my car will be visiting a dyno anytime soon.
again, thanks for the great information (and i do mean that).
400 bucks!?? WOW! I don't even get that for consulting.... Well...ok, if you want to send it go ahead. Does it have to be reported on my Income Tax?
How about this...wait and see what type of intake the new "S" will have, and if it is bigger, use that one to take advantage of larger cams, etc. If Honda uses the same intake manifold and makes increased hp with it, then you know that any modifications to your own intake manifold would be essentially meaningless.
I believe the idea behind the gasket and spacer is to use a material that doesn't conduct heat as well as the stock metal parts, in an effort to reduce intake air temperatures. I have heard that there can be easily noticeable, (to the touch),differences in the surface temperature of the intake and intake manifold. However, I'm not really sure how much thermal energy would be transfered from the walls of the intake system to the intake air..
yup...400. but i paid you 500 already, so you owe me 100 :).
to the last poster...the gaskets are designed to reduce heat soak but the spacer i believe is made of the same material as the whole intake manifold (but i'll have to verify) so i dont see the heat reduction as an intended design.
OK, check's in the mail.... Yeah! Now that is something that I didn't consider. If the gasket and spacer is for heat reduction at the throttle body, that can help. So, maybe after all that posting, you may be right after all.... Mea culpa! Mea culpa!
I'm not sure what it is about heat and throttlebodies, but heat is critical and any way to reduce the heat always helps. There are so many tests of this fact published on the Internet from every type of dyno out there, and some are very reputable, that it is now accepted--reduce the heat and gain hp.
A friend and I (this friend won his class in the Baja 1000 that year) tried an experiment. We rigged up a hose from the A/C directly to the cold air intake of his racing pickup. Turned on the A/C and it was like somebody had added another cylinder to the engine--instant hp! On a hot day, cooling everything in the intake track makes hp.
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