I have several questions for those that have traveled the forced induction road. I am just finishing my TT project that started as a used Bell kit. I chucked the lousy intercoolers for a closed loop air/ water Vortech type that has two Hella water pumps and a large radiator up front. Also re-worked and coated the plumbing from my Mugen headers (yes I cut my mugen's) to the turbo. This included making new cat bypass pipes and eliminating the slip joints for the ball pivot type. I found that the biggest challenge with adding ANY item to this car is getting it to fit in the little air spaces. I also swaped out the Bell fuel control for the Greddy e-manage system and am getting ready for tunning. I am going to wire up the car like a lab rat with air/ fuel, egt and several temp indicators with the tunner working the laptop. Here are my questions. Is it even worth having a air fuel meeter unless it is wide band. I am thinking the cheap ones are to slow. The water pumps will have a temp switch and I figure the after cooler inlet temp around 175 deg on a 75 deg day. Oh, I am set for 6.5 psi bost so far. What temp should pumps turn on and off. Any other tuunning tips would be appreciated as I would rather not damage my engine. Thanks, Dan
Twin turbo hybred
- Thread starter tunapie
- Start date
I say buy a greddy EGT and a/f ratio gauge I have them in my 3000GT and works great and will help you out tuning ur beast. Don't forget to get a good boost controller. what turbos are u slapping on?
Save your money. Any lamda meter that hooks up to the stock O2 sensor is not accurate enough or fast enough for tuning. They will tell you if something is totally screwed up and the look kewl, but that is it. ON the plus side, if you tune it on a dyno, they will have a wide band O2 sensor there (if they are any good at all).
Run them all the time. If they work, the intake temp should be within 20 degrees (guess) of ambient. No reason not to run them and they will be much less prone to heat soak.
See above for temp.
EGT gauge is good while running the car, as it will let you know instantly if something is wrong.
Set the A/F ratio at 12.2 or so on boost. Go from 14.7-14.5 at idle and curve it back to 12.2 as boost rises. If you run there for a while ( esp in summer) without problems, you might try creeping up on the AF ratio a bit, but I would not go a whole lot past that. EGT will help with this.
Timming is a guess, but you are going to have to pull several degrees at full booost. Just dial it back slowly until it works and make sure you retard it enough that there is no predetonation at 6.5 psi at the max intake charge temp you expect.
Use plugs at least one step colder than stock and check them after about a week of normal driving to see if the temip is right. If you go too cold, they will foul in traffic/slow driving.
Don't need a boost controller if you are using the Aerodyne VVN turbos.
Good luck with your project and welcome to the world of forced induction.
Thanks for the info David, to bad you do not live down the street from me. I have a switch so I can run the pumps all the time for track use. The rest of the time I was hoping to cut down on the noise and wear on the pumps. I have a fully adj switch that can be set for different open and close temps. Its just another project on the list. The efficiency of the after cooler and oil cooler will be figured with a cool four sensor box that gives the delta. I will post when I get a chance to beat the car on a hot day on the track. A lot of time went into the oil cooler design. Most people have no idea how high their temps are getting
(like 300 deg +) on the track. Throw in the forced ind. and it is even worse. Dan
(like 300 deg +) on the track. Throw in the forced ind. and it is even worse. Dan
I started to type in numbers for you, then realized there is a better answer. Keep in mind that EGT is just a surrogate for the Lambda value. While you are dyno tuning the car, pay attention to the EGTs and see what you are getting when you KNOW the A/F ratio is correct. That will give you the best baseliine.
Also, some more (random) thoughts on tuning.
1) Most of the time when someone is lifting a head it is not because they are getting too much pressure, but because they are getting it at the wrong time. There are two factors - the rate at which the fuel burns and how what the resulting lag equates to in degrees of rotation. You want to get maximum cylinder pressure at around 12 (maybe 14) degrees ATDC. This is because of the geometry of the crank and rods. You want the rod to turn over before you generate maximum force (cylinder pressure).
2) The general notion is that retarding the timming costs hp. This is not true. While a SBC may need 45 degrees or so of timming advance to make maximum hp, the pentaroof head designs on Honda motors allow for a much faster flame front because it has two squish areas that both efficiently push the mix towards the center of the combustion chamber.
3) So, when you get to the ragged edge on setting the timing, back off a bit. I will use an exampe (made up numbers) to explain why. Let's say you are at 18 degrees and produce a maximum cylinder pressure of 2000 psi. Pushing the timing to 20 degrees might give you another ten hp, but at the same time the maximum cylinder pressure might jump to 2400 psi. That's a twenty percent increase in pressure beating on the reciprocating parts for a tiny hp gain. Back off from the ragged edge and you get 95% of the hp with much better reliability. Hope this makes some sense - I am not sure I did a very good job of explaining it.
Good luck.
Similar threads
Forced Induction
F/S: Single Turbo Kit, Tein Coilovers and OEM Crank Damper