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That isn't true. We have many supercharger kits on K-Jet cars and they are just fine. Many years and many miles on them. The key is a complete understanding of the K-Jet air metering system, and the right engineering to size a supercharger kit to what the K-Jet can fuel - which is what we have done. The K-Jet and early L-Jet cars have excellent camshafts for supercharging, and low compression too - also a + compared to the 32v cars.
I have dyno charts that show the K-Jet fueling the system just fine. And because the 16v distributer can be adjusted, dialing the ignition advance back a bit is a simple thing.
The Stage 1 kit start at just $4895.00 complete.
That equals $6,900 AUD not including 10% sales tax and shipping.
Time to look at an LS/LT swap, or just leave it stock.
That equals $6,900 AUD not including 10% sales tax and shipping.
Time to look at an LS/LT swap, or just leave it stock.
The only thing cheap about a 928, is oil and gas. If you're going to ruin it with a Chevy engine, sell it and buy a Corvette. Besides 5K, for a complete supercharger set up isn't expensive.
Justin ,
If I knew or had the skills to do an engine swap and make it work I would do it in an heart beat, I read with anticipation the trials that tony has gone through with his swap and he spares no expense, doing it A+ all the way, I suspect he has way more than 10k in just the engine and brain....
Putting a chevy engine into a 928 isn't ruining it. It makes a lot of sense, which is why a lot of people do it.
Why would I want to buy an inferior vehicle like an American car ? I would rather spend 8-10k on my Mercedes AMG. That is a German car by the way. You might wish to google about them.
I don't have an issue with a centrifugal supercharger per se, but a twin screw is better.
Putting a chevy engine into a 928 isn't ruining it. It makes a lot of sense, which is why a lot of people do it.
Many feel the 928 engine, which the car was practically designed around, is part of the pedigree that makes the 928 such a great car. Sure you could also make a classic V12 Ferrari faster by yanking out that motor for a Chevy one, but why would you? Many feel the same about the 928 engine.
Also, for the average home mechanic who is not capable of doing such an engine swap without hiring someone or buying a complete kit, the cost of such swaps can easily exceed a supercharger or turbocharger upgrade via one of the available kits.
So once you figure in the cost for most people, the boosted kits don't seem so expensive after-all. Especially if the goal is 500rwhp or more like the Murf928 kit can produce with a 32V car. A decent LS motor that makes that kind of power isn't exactly cheap. At least at the quality level I personally would find acceptable.
I have a longer history with Corvette's than 928's, the plethora of performance parts is a gift and a curse, there's a lot of garbage out there.
I have nothing against engine swaps personally, as long as they are well completed and work (most end up looking like a rats nests of cobbled up wires) but I'd never do one myself.
I like the 928 engine so much I might drop one into my replica Cobra.
There are a lot of 928's that have been laid up for years. Once they get looked at the condition of their engines is such that they need a LOT of work.
So, you can either try and rebuild/resuscitate a Porsche engine that's been out of production for over a quarter of a century, or you can ditch it for a cheap and numerous engine that you can practically buy parts for at the supermarket, and where getting 400+ HP is trivial.
In a lot of cases the options are either junk the car, or do an engine swap.
Like I said, I don't have a 32V engine. This limits my options severely it would seem.
I'm investigating a M112 on the EFI 16V with aftermarket ECU. Maybe it's possible, maybe not. I will need to fab my own intake and intercooler etc....but I did that for my M90/1uzfe engine swap, so I can't see at this point why it's not doable. I have a M112 laying around.
There's no trans control unit to bother with, so that's one thing.
The Powerdyne setup I have on my '79 K-Jet mechanical fuel injected 928 is superb. I've been driving it around with the supercharger removed for a few weeks and it's not the same car - it's nice, and I've enjoyed feeling what an original 928 drove like, but definitely miss the 130 HP increase I was getting with my forced induction setup. My kit is a Stage 2 with heat exchanger from 928 Motorsports. I've been driving it without it because I sent the supercharger head itself back to them for an upgrade to find a little more boost - lighter, billet machined impeller with different vane design, upgraded bearing, stronger internal belt, and vented the case. Here it is reinstalled, but I'm waiting for some different upper radiator hoses that arrive this week.
Airbox work and powdercoating I did custom and are not part of the 928MS kit.
The car makes 350 HP & 350 TQ at the motor (about 292 HP at the wheels) and that was prior to these supercharger upgrades, so figuring a bit higher now - maybe knocking on the door of 400 HP. Tracking AFR values, it's always between 11.5 and 13.5 and under full throttle closer to the 11.5 - 12 value, so definitely on the richer (safer) side. The K-Jet system, when in good operating condition and setup properly, works just fine for supercharging, as it adjusts the fueling to correlate to the air it's metering. I will be closely watching the AFR values when I do the first couple drives with the upgrades, as I want to make sure the fueling will still match up to the increased air, and not lean out under high RPM, high boost situations.
Both the car and the supercharger have been perfectly reliable since I built it 4 years ago. If you want a HP & TQ monster, then starting with the 32V motor is surely the way to go, but when I saw this convertible, I bought it for the body style and then wanted to make it perform a bit better than stock, which is why I spent the money to upgrade a 16v motor and the rest of the car - 6-speed transmission, GTS brakes, Konis with sport springs, etc.
It's a lot of fun to drive and has the right balance of comfort, power, and cool-ness.
I’ve got a 1980 16V 928 Spyder that was converted in California almost 20 years ago. I put a 928Motorsports stage 2 J-tronics kit on the car 5 years ago which looks identical to yours but have had consistent heat management issues in summer traffic. Replaced the stock radiator, upgraded fan assembly, water wetter- all the obvious mods but no luck. Thinking about trying Fan shroud mods but running out of ideas.
I’ve got a 1980 16V 928 Spyder that was converted in California almost 20 years ago. I put a 928Motorsports stage 2 J-tronics kit on the car 5 years ago which looks identical to yours but have had consistent heat management issues in summer traffic. Replaced the stock radiator, upgraded fan assembly, water wetter- all the obvious mods but no luck. Thinking about trying Fan shroud mods but running out of ideas.
Richard
Alexandria, VA
Richard, do you have the same fan and controller setup I have (black box with ****). Mine also has 2 smaller puller fans on the back side of the radiator, so the large fan on the front pushes the air through and the two smaller fans on the back pull the air through. All 3 of them turn on together and that temperature setting can be selected using the **** on the fan controller (the black box). My car runs just above the first white line on the temp gauge under normal cruising situations as long as there is good air flow into the front of the car, without the fans running at all. I have the controller set to turn the fans on at the middle of the gauge (right between the 1st and second white lines), and with the fans on, the needle never goes beyond the second white line even when sitting in stop and go traffic in the summer.
If you have the same setup, but are still having overheating issues, I would first make sure your fan(s) are running, and also make sure they're running in the proper direction. I've seen someones car where the puller fans on the back were actually running the opposite way and pushing air back into the radiator working against the front mounted pusher fan. If the fans work and work the right way, then pressure test the cooling system. Any loss of pressure means the coolant will boil at a lower temperature and not pull heat effectively. Also test your coolant cap. I think mine says 7 psi right on it and tested right at about that pressure. Since fixing my recent coolant leak at the water bridge and the previous coolant leak at the radiator tube, now that the system holds pressure perfectly, the temps are very predictable and steady. Prior to that, it would get too warm if sitting in stop and go traffic, like a parade I did a couple years ago.
Let me know if you need more pictures of the fan setup or controller setup.
I'd also love to see pictures of your car. Do you know who the California Coachbuilder of your convertible was. I've never been able to find out who built mine, just who didn't (it's not a Carelli, Wingho, or a Gene Winfield).
isn't a 7 psi cap a bit "low" for a FI engine ? better a 13 psi… or even 20 psi ?
the lower the pressure , the sooner water can boil and have steam pockets , ( at the exhaust valves ? ) , and steam doesn't cool the metal as water would have done …. much worse.
I thought the 7 psi caps were to "protect" old radiators/hoses from to high pressures and cracks/leaks …. but on a oem engine....
The coolant caps we have up here in the north with the cold viking climate (well it is supposed to change for warmer if we stop driving our 928 cars and stop eating meat) are all marked one bar which is the same as 14.5 psi.
Åke
Last edited by Strosek Ultra; 10-14-2019 at 11:22 AM.
isn't a 7 psi cap a bit "low" for a FI engine ? better a 13 psi… or even 20 psi ?
the lower the pressure , the sooner water can boil and have steam pockets , ( at the exhaust valves ? ) , and steam doesn't cool the metal as water would have done …. much worse.
I thought the 7 psi caps were to "protect" old radiators/hoses from to high pressures and cracks/leaks …. but on a oem engine....
I don't know. This is the cap that 928MS installed with their radiator and aluminum coolant reservoir. Seems to be working just fine based on my temperature readings, but maybe a slightly higher pressure one would have some additional benefits.
i have that same cap from 928MS , must have been with parts in 2008....
I would not use that : water can boil at 110°C under 7 psi , so if on a "spot" water gets 110°C there is evaporation… steam bubble , with bad heat transfer to the metal
14.7 psi gives 120 °C
20 psi 126 °C
so it is safer to use at least a 14.7 ( 1 bar ) cap.... if you radiator and hoses can take that of course.
We like to use the 7 psi cap when we see 30+ year old stock radiators on 16v cars. It helps our customers get a few more years from their radiators before the end caps fail.
I agree with Barry (above) - making more HP means making more heat - I'd go with a 14 psi cap on a supercharged motor myself.
02-21-2019, 08:04 AM
