slant 6 rebuild and upgrade list
As for the CR and boost, the fact that a car will run 12 seconds is not going to mean it will be 'snappy' on the street. That is the point that is being made; at the strip, you have already revved up and gotten the turbo spooled before ever dropping the hammer, so the boost and power is there. On the street, that is not going to be the case very often and the turbo lag is what if going to make it 'un-snappy'.
Having said that, there are things that can be done.
- Push the CR up in the low 8's IMHO; in my rally building engine experience, running in the 9 range and any boost at all in the 10+psi range requires some pretty good tuning; rally cars are now running 10+:1 SCR and gobs of boost, but they are all HIGHLY engineered with tons of $$ invested and special fuels, EFI of course, etc. I have rallied 14-15 psi boost on a true 8.2 SCR with just so-so tuning and premium. But I don't view the /6 bottom end to be particularly strong so personally would be cautious.
- Look long and hard at the turbos available and be ready to spend some extra for the right one. The spool up can be very greatly modified by the exhaust impeller design. My last Super 16G (on a Mitsu 2.6L) is already turning and 'burbling' at idle; the spool-up is a ton better than typical.
BTW, the published CR's are not accurate so don't assume that number is where you are starting.
BTW#2, add at least 2.5" or even 3" exhaust to your list to help the turbo.
Should be interesting.
Thanks, Snappy to me meant "Expressway" speeds and staying there or passing, which means the turbo should be spooled up a bit and not too "laggy". heck I'm not worried about off the line performance at all since it's a driver for pleasure. my original /6 was just too sluggish at highway speeds to be enjoyable, it got off the red light pretty good but just did not have the oomph at 55-70. I wanted a "top down cruising down the road and it'll wake up and pass what I need to but run all day" experience. (ya don't usually put power windos,seats and A/C on a drag car do ya?:))
I have just finished going to charlie_s place and talked to him about the setup I'm wanting. Some of my do's became don'ts and I have added to the list of needs and 2.5-3" is in the works after mock-up.
Yes, I'm going bigger valves. a bit of porting to smooth everything out (in the bowl area for sure) 1.44 and 1.70. after the head is back from the shop I'll take the block in and see where that falls in at for pistons. before any more work is done on the block I'll pop the head on it minus pistons and check for shrouding and where it needs to be worked on to clean it up. then I'll get the pistons , check how far it is in the hole and see if I can get the compression up to a good "turbo" compression since 9 to 1 does not seem to be where I want to go with the /6 at this time.
here is my figures
59cc heads
3.4 bore (as stock right now)
4.125 stroke
.165 in the hole (stock)
.040 head gasket crush (fel-pro measures off of old gasket from block)
my measurements using these numbers approx. come out to
7.85 and I'd like to move it up just a bit, but until I find out how the new pistons stack up I'm not getting anything cut until I have measured it.
Displacement = (Bore ÷ 2)2 x 3.14 x Stroke x 16.387
Head Gasket space = (Bore ÷ 2)2 x 3.14 x Gasket thickness x 16.387064
Deck Height space = (Bore ÷ 2)2 x 3.14 x Deck Height x 16.387064
Compressed Volume = Head Gasket space + Deck Height space +
Piston Top volume + Combustion chamber volume
Uncompressed Volume = Compressed Volume + Displacement
Compression Ratio = Uncompressed volume ÷ Compressed volume
I am about 9/10th of the way money wise to get the megasquirt II setup for the engine and needed cabling put on order.
now to get a solid manifold that I can use or make my own.
I have the AEM 304110 lsu4.9 wideband gauge and sensor, boost gauge , egt gauge and a 4.0 jeep,LS350, ford 302 throttle body. one of those might just work for me.
I have been in contact with Oregon cam grinding and after talking to Ken heard suggestion I'm going with the 819 grind.
"#819" 219/219 @ .050”, 264/264 adv(.014”), .437”/.437” lift, 110 sep (changed to 114 separation) and all new lifters
not quite as aggressive as I though I'd need but a "little" bit over a stock cam with a good idle. Cam goes out tomorrow (10-11-2016)
I'm still deciding on exactly which turbo to go for. open scroll Vs split scroll ect. I'm having trouble trying to read the compressor patterns and which one would be best for a mild 8-10 psi application I.E spooling fast and not running out of steam till 5k. Which does rules out the tiny china "tuner" turbo's on ebay. I would like to read the darn maps correctly. been googling everything I can about reading compressor maps. the more I learn the more questions I have %$^$%^,I seem to never get out of school!
