E pistons in a DE. direct replacement? + P&P Q's

[DriftingisLame]

Hey I was just wondering if putting the E pistons in my DOHC motor would be such a good idea. It will be my daily driver, and I was wondering if 11:1 or 11.5:1 comp is way too high for a mostly stock KA. What modifications would I need for this high of a compression jump? Would some form of fuel managment be helpful, such as an SAFC? When I searched about high comp KA's i heard someone talking about valve clearance on really high comp KA's. should I be worried about this with the E pistons? Are they a direct replacement with the DE pistons? Would a thicker head gasket a reasonable solution for lowering the comp a little bit and getting some more valve clearance?

Also while the motor's out I was thinking about rebuilding the head and trying a P&P. My friend says his dad has all the stuff for doing a P&P (Porsche mechanic for 10 years, then VW for 25) and he's done countless P&P jobs on some mk1-2 VW 8v and maybe 16v heads. Would the KA head be very easy to do a P&P job on? Any info you have on this would be greatly appreciated as I have no experience here.

If you could let me know anything I really need to watch out for with both of these mods please post!

I searched, if I missed something and I'm reposting...I apologize!

thanks!

-Max

[1991S13]

Sorry I can't help you with the E piston question. I am pretty sure I read in the past that they drop right in though.

Also I once read (I do a lot of that, lol) that you won't really notice that much of a gain from a port and polish on a street driven KA. I mean if you are getting it for free or real cheap since it's a friend's dad then go ahead, but I don't know if I would pay a lot of money for something with not that much of a gain.

[DriftingisLame]

Hmm, okay. I was looking for some more specific info, but thank you, everything helps!

Anyone else?

[PandaS14]

With stock cams you wont' have any valve clearance issues.

As for P&P. Your engine is an air pump. The more you pump, the more power you make. So naturally increasing the ease of and amount of air flow into and out of the chambers is a must. There are many other intake and exhaust related mods to do first that help get air into and out of your engine in a fast, efficient manner. But the head is the most critical of all of of those components. So if you plan on trying to make any real power with this motor, I highly suggest a P&P. Lets also not forget that a good P&P will help atomize and mix the fuel/air better.

[DriftingisLame]

Yeah I am aware of the gains and importance of a P&P on an NA motor, I am just wondering if it should be a newbie DIY project I should attempt. I know I have my friends dad to help, but for some reason I think an 8v 1.8l motor invented in the 1970's would be a lot less complex than the KA24DE. I have never done a P&P before, I could really use some warnings and such.

Thanks for the input though!

[DriftingisLame]

Oh, also... would I have clearance issues if I had dual exhaust cams?

[eddiec]

you'll be ok with the late E pistons. its the early years that had the larger dome requiring some modifications. the early years give ~11.5:1 and the later years give 11.1:1.

heres a link i have about P&Phttp://www.sa-motorsports.com/diyport.shtm

P&P is always a good idea. but w/o suppting mods you will not notice it much due to restrictions elsewhere. now if its free and everything is torn down then yeah go for it. just be careful and take your time if you DIY. if have an extra head that i fiddle with every once in a while.

[thekage]

I heard that if you drop in E pistons.. you also need E rods?

I am going to rering the pistons out of my E and install them in my DE as well....Do I need the rods?

[PandaS14]

Nope, stock DE rods.

And putting used pistons in an engine is a horrible idea. Very big chance they won't seal, as well as different wear patterns that are sure to conflict and cause even more probs. a brand new set of E pistons with rings is only $155.

[DriftingisLame]

Great this is lookin good for my project.

Will 11:1 compression be a bad idea for a daily driven KA? Will I need to use gas with a higher octane rating than 92? Will a really thick headgasket lower the compression somewhat effectively?

Thank you for the help! Great link eddiec.

[PandaS14]

yeah, you can run that on 92 octane. Probably won't be able to advance timing much, but you should be fine.

Yes, you could get a thicker HG to lower compression a bit, but at that point you might as well just get 10.5:1 pistons.

[DriftingisLame]

well most of the reason that I thought going with the E pistons is because of the cost... Normal high comp pistons wouldnt be as cheap.

Unless your saying that because the cost of the HG + pistons would be as much as 10.5:1's. In which case I would still come out with a nice new HG and high comp pistons.

Is there any other mod's I should do to make this more safe? Or is this literally just direct replacement? Would an SAFC be a good idea? I'd like to pick up an SAFC just to learn about basic tuning anyway, but what would I do to the mixture with the high comp?

And I know this is a pretty broad question, but with a slight P&P, IHE, and maybe the SAFC, what kind of gains would I be looking at?

Thanks!

[DriftingisLame]

Anyone?

[PandaS14]

well then just go sohc pistons. I don't know why you are set on getting a thicker HG? You won't have any probs with stock cams and hg. You won't need any extra fuel management, but you would see better gains.

As for power, who knows. They're all different. do some searches.

[DriftingisLame]

Cool, thanks.