mark kibort

Amazingly enough, compression is still exactly like I had when i first dynoed the car! 190psi per hole. HP was down to 298rwhp, but I still think it was dyno operator error in strapping it down too much by a new helper at the shop.
Even still, the most HP it ever made was 330, a couple of years later it leveled out at 320rwhp and stayed there until the last dyno run.
With running the same lap times at laguna since 2002, the engine really has not lost much if anything.

So it probably makes sense to run the car for the remainder of the season.

Mk

Black Sea RD

Mark,

Great news.

This will also give you some time to get the correct parts to finish the stroker. Heck, how about adding a huffer to the stroker? Just thinking out loud...

Constantine

mark kibort

What about those cometic head gaskets? anyone run those today on a 928? (particularly a stroker?)
any downside vs the stock 968 gaskets or what ever most use for headgaskets? (risks?)

mk

BC

Since I know the block was assembled and surfaced properly my Todd, I know that I can suggest that you can use the cometics AS LONG as you get the heads properly leveled and surfaced. But not by some monkey shop who uses 18th century sandpaper. It has to be around 50ra on both surfaces, and then for extra measure you can use hylomar.

Its an extra measure to make sure the engine stays together.

What about having todd clean up the heads?

Kaz

Pull the engine now and start winning!!

BC

6.5L needs something on the heads and intake to breath where you are reving the engine. You need a scraper. You need to have time to do it properly, and not be scratching around on the ground of a garage getting it ready. There is a reason that production engines are built in a clean room environment.

mark kibort

are there any stock S4 conversions with only the 6.5 liter change?
my friend randy did the stock everything, GT Cams and the head work. (larger valves and some porting) he made 430rwhp. I have to imagine without the head work, it should only be worth 20-30hp. If thats the case, im in good shape. However, if my heads and intake can only flow enough to make 60 more hp out of a 1.5 liter increase in displacement, I will have to think hard about additional mods.

Mk

Black Sea RD

Put on a twin screw, that should help.

BC

I just don't understand where anyone would think that adding 1.5L to a car requires no intake and exhaust flow mods. There is some moderately easy work that can be had on the heads after the 968 intake valves are added. You also should focus on getting cams - probably something ground from the S3 cams you already have in there.

H2

I would like to see the Holbert engine pulled and carefully documented by someone like Greg Brown to verify what enhancements were made to it when it was originally built. Then, rebuild it with new parts and put it back on the road. I'd love to have an engine built to those specs. It can't be fully factory stockl.

H2

mark kibort

odds are, it is. It put down the exact same hp as a GT motor did with the same mods. (headers) both were 320ish rwhp and the curves were almost identical. Mine did have a slightly broader HP curve way up near 6000 to 6500rpm, but it was slight.

I think if there is anything different, it might be in the oiling or tolerances. However, we are seeing similar performance and longevity out of Scots 5 liter euro that i built.

Mark

mark kibort

because there are plenty of 5.7 to 6.5 liter engines out there with far more restrictive intakes. Adding 1.5 liter does add 20% more mass flow. In fact, if there are no changes and the 5 liter intake was maxed out, there could be some of the same HP found in the lower rpms of the larger engine. Because we know that the 5 liter heads still flow pretty well, AND that the intake can support 420rwhp with no mods (and that mods havent yeilded any improvments for the 6.5 liter, as was seen in Mark A.'s engine) I would think that 1.5 liter would add substantial HP, as well as the agreed increases in torque.

Again, If andersons engine made 420rwhp with only heads and cams, we have to ask, what did those mods make? 10-20-30hp??? There is plenty of documentation of restrictor plates only dropping 20hp with a 40% restrictor in some racing series.

I guess we will see. what i will do, since i will now have the time, will be to port match the intake ports and extrude hone the intake. other than that, besides the larger injectors, i will be putting it all back together as it is now, but with the different bottom end.

Keep in mind, the car did make 335rwhp before i started racing it seriously. It later fell to about 325rwhp for several years and now ending up in the 305rwhp range after 7 full racing seasons.

There is no indication on the HP curves, that its running into any flow issues at max rpms, actually quite the contrary.

I think expecting 75-85hp from the 1.5 liters, and maybe a little more due to the engines inherent racing design advantages. Heck we bolted on 300ccs to scots engine and it instantly gained 40hp, with no other changes.

The stock S4 heads are pretty nice. 3.5" throttle body, 3.5" MAF, albeit a little restrictive intake. BUT, even a stock S4 went from 266rwhp to 320rwhp with only a 6 liter adder. (but with cats, stock S4 cams, etc). With the GT cams (same as holbert car), equal length headers, race exhaust, etc, I would think the car will breath fine.

Im surprised there are no stock 6.5 liter dynos. There is a GTS conversion, that only had a head modification and did 400rwhp and 420 after tuning. (stock intake, exhaust, cats, etc)

Mark



mk

BC

Ok Mark

mark kibort

Well, after this weekend's event, I'm reconsidering putting the stroker block in.

mathematically, its possible that i could still pull off the championship, but the S2000 would have to break, which has happend already 2 times this year, and i would have to beat the Vet in the next 4 races at Sears and laguna, where he has proved to be faster recently at laguna only, but there is no reason to think that he shouldnt be a problem at sears. (2 races at sears, laguna and 1 at T-hill left)

even if i do beat him for the next 4 races, the S2000 SC would be a head of me as well, and I only have an 8pt lead, so he would beat both the vet and me in the last race at Thunderhill in Nov.

so, im lookinig at 3rd, no matter how you slice it if the two cars in front dont break and we all do what we have been doing over the last 8 races!

If I put the engine in now, and get it broken-in, dyno tuned (checked for fuel) and ready to go by the end of the month, there is a good chance i could win the next few races and pull off a championship.
However, the downside is a cooling issue or failure, could put me out of a race or worse.

Im pretty busy at work, and dont know if i could pull it off in time. plus, i was thinking of doing some hand porting over the winter with the intake and heads.

Right now, the list is set at near 50-50 from doing this now or later.

I also am a little nervous about the shortblock still. I just cant see how the pistons can move so much in the bore (side to side), even though the tops are supposed to be smaller than the skirts and they are shorter than porsche stock. seeing a picture of another nicasil block assembled would sure make me feel more comfortable! anyone got any? spec is .004" at the skirts and im seeing well over .020" on the tops. anyone know the difference of the tops vs bottoms on JE pistons?

mk

bcdavis

Do it right.

Then have a totally successful season next year.

Better to dominate next year, and win every race against those guys, rather than squeaking out a win this year at the risk of losing the engine or having problems that put you out of the running. If you win most of the races next year, and something goes wrong, you can be out a race or two, fix things, get back in there, and still win the championship.

I also look at your long-term history of not fixing things when they break. Remember the broken cam teeth? So if you get the new engine running right now, you will probably just leave it alone, and not disassemble it this winter to redo everything. I just think it would be so much better to take your time with it. Especially for the first time installation. If it has problems during next year's season, then you can rip it apart for quick repairs if you need to. But I think it makes a lot of sense to take the time to put everything together right. Ideally, it will stay together, and problem free, for many years to come. Then you won't have to mess with anything. If you do it right to begin with, you won't have to pull it apart every couple races to figure out why things are going wrong. You can just focus on driving and winning.