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While we are on the subject of 3 and 2 bar GM map sensors... Here is how you can identify what type of map sensor you have. Don't be like me and assume you have a 3 bar and tune with the 3 bar settings when you actually have a 2 bar (because that is what the kid who sold it to you told you it was).

Anyway here is the site that helped me find the problem.
http://www.robietherobot.com/storm/mapsensor.htm
 

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what about compression ratios. i.e. with the edelbrock kit on a z6, in the ad it claims 260-280 hp at the crank. in fine print it says basically claims like this are achieved with pistons, cams, rods, etc. what would be an optimal c/r to achieve gains like this? also, cam profiles...what would be a good lift/duration along with pistons for these gains? i'm a do-it-youselfer and would rather learn to tune myself than to pay someone to do it. then i know exactly where i went wrong, and can diagnos the problem on my own
 

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R2.....Zap Balls
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5,186 Posts
very nice, I read this sticky alot for info. Hopefully I can get my ebc set up correctly, I'm still fiddling with the set and gain on it :lol:
 

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R2.....Zap Balls
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Boost Spike vs. Boost Creep

I came across this on another site, I didn't see anything mentioned in the previous post and fig it would be helpful :D
Since these two terms are very commonly used in describing turbo/engine behavior, yet they are not always understood correctly, I wanted to attempt to clear them up.

People often mix the two up, or even interchange them, when they are in fact two VERY different things.

Boost Spike: Boost spike is when the boost level initially "spikes" up to higher than the preset boost setting, and then quickly settles back down to where it should be. As most people with turbos know, once the boost pressure in the intake starts to rise, the rate at which it rises quickly increases until the pressure is increasing at a phenomenal rate. This means that, if your boost is set at 12 psi, when it reaches that point it will be increasing so quickly that it will go higher than 12 psi and then drop back down once the boost control system can correct it, which is within a half second or so.

Some causes of spike are bad boost controllers (only ball-and spring type MBC's should be used, and only proven electronic boost controllers should be used), long boost source or wastegate activation hoses, and the lack of any boost controller at all. It's basicially an effect a t slow response time of the boost control system.



Boost Creep: While boost creep also refers to an unwanted rise in manifold pressure, its cause and effect are totally different from those of spike, as is the way it manifests itself.

As you know, boost pressure is controlled by the wastegate, which allows exhaust gasses to bypass the turbine wheel. In effect, it creates an alternate route for the hot exhaust coming out of the motor to take, which means that any gas passing through it will not spin the turbine wheel.

Now, if this wastegate cannot flow enough to bypass the required amount of exhaust, then that means that too much of the gasses are going to go through the turbine wheel, meaning that it will have too much energy imparted on it (it will be spinning too fast). As the excess exhaust gas amount gets greater and greater, the turbine wheel spins faster and faster, and the boost level rises.

Creep happens ANY time when the wastegate cannot bypass enough exhaust gas to keep the boost under control. This can happen when the wastegate is too small in diameter, or when the design of the wastegate doesn't allow it to open enough, or when the wastegate simply doesn't have a good enough flow path to divert a lot of exhaust. It can also happen when you increase the amount of exhaust coming out of a motor (running more boost/airflow, making more power).

Since this tends to get worse and worse as the engine speed rises (more cycles per second is more conducive to more exhaust gas, to a point), that means that one will see the boost climb to the preset level on the boost controller, and then it will gradually creep up past that line to a "minimum" given the circumstances.

That minimum can be 2 psi above the set boost level, or it can be over 30 psi, depending on how the wastegate is designed, how big it is, the car's setup, and more.

It is also important to not that you certainly can have spike AND creep at the same time, which would result in the boost level jumping up, settling to the preset level, and then slowly climbing back up again as you approach redline.
 

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my q is do i need certain valves? b/c i saw the supertech valves n than the omni power 1's n i wana kno the deminsions on certain companies make a difference? b/c the superflow ferrea valves design dont look like anybody else's...like the actual degree of curve on exhaust n intake valve...whats the deal...can some1 help me plz!
 

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the MAD scientist
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Lets just keep this thread for posting information. If you have a question please start a new thread.

But to answer your question, my only advice would be to call the companies that make the valves and ask them for the dimentions.
 

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How long should I let the turbo cool after driving the car? I try and take it easy the last mile or so of my drive, and I let the car idle for about a minute before I shut it down. I don't want to cook the bearings. I've heard of problems w/ aftermarket alarms and turbo timers.
 

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the way i build my pcv system:



deleted the stock pcv system (dont forget to close the hose from intake to back of engine)

than run hoses from the valvecover and from the black box (on back of engine, under intake) to a catchcan... make sure the catchcan got a breather filter!! (or at least can vent)

you just have to empty the can sometimes, or run a hose from the bottom of it to underneath the car (could be dangerous!! you don't want oil on your tires, is not on drawing)

feel free to comment if there's something wrong in your opinion

i've been driving this way ever since i got boost, no problems at all with the vent system :bravo:
 

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nice write up but,???

ok i have been helped out alot, but still the answer is out of reach for me. i am currently in the process of building up my homemade kit. have t3 flanged manifold and downpipe. looking to get a t3 with 48 a/r trim snail. 450 dsm injectors and bov. still saving up to get intercooler,wastegate, piping, afpr, air/fuel and boost gauge. so now i have learned that i need colder plugs, and catch can. the problem is that a have the apexi vafcII and confused. so the hack is not good or is it just not good on high boosted motors? i plan on running 5 to 7 psi of boost on a d16z6. and another thing, on the wastegate,how do i know which spring gives me what pressure? all i saw was the sizing (38,40,etc.). and do i have to make my own dump tube since there is none on my downpipe? thanks for any help and it well be greatly appreciated. pm me if possible....:hammer:
 
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