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Car Forum / Mazda / Mazda Miata / July 2005MX5 HKS turbo charged...questions.
Hi MX5'ers Currently looking at a 1992 MX5 1600cc. Its a friends car and I'm new to the MX5 so would like to ask a few questions. The car currently has a HKS T25 turbo kit but nothing else such as intercooler. Engine block and head is completely OE with no modifications whatsoever. I might get an intercooler installed on the car with a boost controller and stronger brakes but apart from that no more. I would like to ask a few questions regarding the engine and gearbox of the MX5. The car in question has 3 previous owners but my friend knows them all. Questions: 1) The gearbox still feels tight as its only covered 15,000miles, true or not hard to say. It's a 1992 model so any known faults from this year or common problems that need attention? The car will only be used for weekends as a fun car and project car for power. 2)Well maybe get new suspension too but which brand and type is best for the MX5? I am looking for a firm yet comfortable ride without ruining the car's excellent handling? 3)What kind of repairs or servicing would I be expected to carry out on such year ? All fluids and such will be changed and brakes checked for function. 4)Considering completely respraying the car so how hard is it to strip down for a good spray job? 5)Whats the max turbo boost one can use from only a T25 installed? Thats all I can think of the time being but if I have left anything out please kindly list. Appreciate all replies and help and who knows I might have the car very soon if all goes well. Thanks and appreicate all replies. Jim First of all, you're highly unlikely to ever regret the purchase / experience. The miata's a great platform in its original form and solid to build on / from. As for maintainence, you might consider the timing belt due to age and stress with the SC but even that isn't critical as it would be in an 'interference engine' so you could even wait on that. I love the adjustability of my KYB AGX shocks and I feel the FM sway bars are the best $200 ever spent on my car! I'd add that tires can make a huge difference in the car. There is endless debate on tires but you would probably be best served by the Toyo T1S's since you won't be putting lotas of miles and probably thier biggest drawback is considered thier price. I'll let others get into the SC'r questions, I, so far, have only dreamed of such decisions! Chris 92BB&T > Hi MX5'ers > [quoted text clipped - 43 lines] > > Jim Hi Chris What spring rates do the KYB shocks use and thickness of the FM bars front and rear? Thanks Jim > First of all, you're highly unlikely to ever regret the purchase / > experience. The miata's a great platform in its original form and solid to [quoted text clipped - 63 lines] > > > > Jim Jim Wrote: "car currently has a HKS T25 turbo kit" "Engine block and head is completely OE with no modifications whatsoever" HUH? That would be a very incompetant modification, highly unlikely anyone with any idea of what they are doing would have done that. For turbocharging to work, you need to somehow lower the engine's compression. Without doing this, a turbo will just make your motor ping a lot. Usually headwork is the easiest way to decrease compression. Unless you have something else, like a spacer head gasket, or an "unstroker" crank, the turbo job is unfinished. The maximum boost depends a lot on how much you have lowered your compression. In your case, you could only have a tiny amount, and are not going to see any significant performance gains. > Hi MX5'ers > [quoted text clipped - 43 lines] > > Jim "Mal Osborne" <noone@nowhere.com> wrote in: > That would be a very incompetant modification, highly unlikely anyone > with any idea of what they are doing would have done that. For > turbocharging to work, you need to somehow lower the engine's compression. Mazda's website shows the Miata has a compression ratio of 10.0:1 and the Miata Speed's ratio is 9.5:1. The difference isn't much and I suspect that going to premium fuel would probably eliminate most pinging.... A 2004 Miata turbo is a very mild turbo job, hence compression is only mildly reduced. Boost is kept low, at 7.25PSI, power is increased by about 25%, but with a narrower delivery curve. Without modifying compression, I guess you could run maybe 5 pounds and get perhaps 15% on standard fuel, a little more on premium. There will be a small weight penalty as well I would not bother, without a compression decrease any power gains will be minimal. > "Mal Osborne" <noone@nowhere.com> wrote in: > [quoted text clipped - 7 lines] > that > going to premium fuel would probably eliminate most pinging.... > Without modifying compression, I > guess you could run maybe 5 pounds and get perhaps 15% on standard fuel, a > little more on premium. There will be a small weight penalty as well > > I would not bother, without a compression decrease any power gains will be > minimal. You might get an argument from hundreds of FM2 owners running 12 psi and getting 225-240 rwhp on stock internals in their daily drivers (a stock 1.6 makes about 90 rwhp). Sure, it's more efficient to lower compression for high boost, but it's expensive, and unnecessary with intercooling and proper engine management. --- Lanny Chambers '94C, St. Louis http://www.hummingbirds.net/alignment.html Lanny Chambers <lanny@hummingbirds.net> wrote in: >> Without modifying compression, I >> guess you could run maybe 5 pounds and get perhaps 15% on standard fuel, a [quoted text clipped - 8 lines] > for high boost, but it's expensive, and unnecessary with intercooling > and proper engine management. People who are used to the "rules" with 500 ci V8 engines with 4" diameter pistons are often confused by what can be done in little bitty (comparitively) combustion chambers. Anyone recall the old Crosley cars? They had the Super Sport version running a 12:1 compression ration back in the 1950s using water/alcohol injection. Had the engine been much larger than 725ccs it would never have worked. > HUH? That would be a very incompetant modification, highly unlikely anyone > with any idea of what they are doing would have done that. For > turbocharging to work, you need to somehow lower the engine's compression. > Without doing this, a turbo will just make your motor ping a lot. I suspect the HKS kit is much like the simple GReddy turbo or JR supercharger kits, which work fine with unmodified engines at 5 psi if the base timing is retarded 6 degrees or so and premium fuel is used (or if an aftermarket boost/timing solution is installed). 5 psi is worth about 35 rwhp on a 1.6; whether or not that's "significant" is a matter of personal perspective; it's certainly tangible, and about as much as the stock clutch can handle reliably. Hundreds if not thousands of MX-5s worldwide are using similar systems. --- Lanny Chambers '94C, St. Louis http://www.hummingbirds.net/alignment.html Jim, Sorry, your post got a bit hijacked. I don't know the sway bar dimensions, I was thinking that FM only sold one front and one rear bar but I could be wrong. As for the springs, I installed the KYB's with the stock springs. I'd heard plenty of people singing the praises of this set up and I really like it. I guess an inch or so of drop would be nice but unless I was really wanting that, or just didn't have any quams about spending the additional cash, I'd stick w/ the stock springs which are reported to be good for the life of this light weight little vehicle. Good luck, Chris >> HUH? That would be a very incompetant modification, highly unlikely >> anyone [quoted text clipped - 17 lines] > '94C, St. Louis > http://www.hummingbirds.net/alignment.html |
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