Hey

Well my DOHC ZC is buying hardcore on me and the engine overall is in poor shape. I managed to trade my brother some parts for a D16Y8. I was planning on turboing my DOHC ZC but things didn't work out so I scrapped my turbo plans.

I need some info. I want a reliable engine, respectively. So here's my plan.

Parts:
- New crank bearings
- New rod bearings
- New OEM head studs (arp if price is right)
- New OEM 97+ headgasket (non composite metal)
- New valve seals
- New rings
- Aluminium flywheel with stock replacement clutch
- New seals where needed

Work:

I have access to a machine shop so:
- Resurfaced head (lose .005")
- Check block for flatness, avoid machine block mating surfacing
- DIY hone using those rent kits (I heard good things and seen proffesionals use those kits)

Upgrades:

- PM3 pistons (http://www.knology.net/~jediklc/dcalc.htm says this will make the CR 11.1:1)

I have rebuilt heads before but never a bottom end. My brother will help me thruout my build so I feel confident that this will get done properly. I am keeping the stock cam, stock IM and stock EM.

My question is, will I need to upgrade any other parts due to the high compression. If so, I may look into PM6 pistons which will make my CR 10.3:1 (beats the 9.7:1 from factory). Also, will I need to port and polish the head. I was thinking about doing a DIY job similar to that of a ITR head. Mainly, removing the flash from the head if need be. I am trying to keep this build as cheap as possible but obviously do it correctly.

I am NOT looking for massive power, but more of a reliable engine with some get up and go. It will be mated to a 91 Si tranny and dropped into my 91 wagon. I will downgrade the fifth gear to an HF 5th for low rpm cruise. I have a obd1 conversion kit and a chipped P28 already.

Let me hear your thoughts/suggestions on this subject. I am planning on buying parts ASAP. The PM3 pistons showed up today from my other brother.

 

Cleaning up the casting marks won't do much at all. Don't try to do any porting yourself.

Keep the Si 5th. You'll get better gas mileage.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Aquafina &raquo;</TD></TR><TR><TD CLASS="quote">Cleaning up the casting marks won't do much at all. Don't try to do any porting yourself.

Keep the Si 5th. You'll get better gas mileage.</TD></TR></TABLE>

I don't see how keeping the Si fifth would yield better gas mileage. Lower RPM tend to yield better gas mileage no?

Anyone have any input, cause the DOHC ZC basically died on me today and it's getting pulled soon.

 

No. Higher RPM = less throttle = more gas in your tank.

I've tried about every D trans setup you can, and 1.000 5th gets me the best mileage.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Aquafina &raquo;</TD></TR><TR><TD CLASS="quote">No. Higher RPM = less throttle = more gas in your tank.

I've tried about every D trans setup you can, and 1.000 5th gets me the best mileage.</TD></TR></TABLE>

Well I cruise on the highway at about 4000rpm in fifth and I don't like that kind of wear on the engine. I'll throw in the hf 5th, if I don't like it, I'll remove it and replace it with the Si 5th. No big deal.

Can anyone input on my question about the need for tuning if I run higher compression? I'm trying to avoid any headaches so I need as much input as possible.

 

Yes, you'll need to have it tuned.

I've put over 16k on my car since I put the 1.000 5th in. Did a compression and leak down test about 1,500k ago and the results didn't show any additional wear. 2 8 hour round trips to Nashville, 1 16 hour roundtrip to DC/Balt, 3 weeks of 85 mile/day trips, the rest local mileage.

 

Oh well, I'm still gonna use the HF 5th. Sometimes asking these questions is to get opinions and decide for yourself.

Damn, I was hoping I could avoid tuning.

 

It is not my opinion I get better gas mileage. It is fact. Unless miles driven / amount of gas is not the correct formula for MPG.

HF 5th will not make a difference from a standard .702 5th.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Aquafina &raquo;</TD></TR><TR><TD CLASS="quote">It is not my opinion I get better gas mileage. It is fact. Unless miles driven / amount of gas is not the correct formula for MPG.

HF 5th will not make a difference from a standard .702 5th.</TD></TR></TABLE>

Different strokes for different folks. I'm installing the HF 5th, so move on. If you want to keep bugging about it I won't read it. If you wanna input more on what upgrades need to be done for me to run 11.1:1 CR safely then please continue the discussion.

 

There is nothing really to discuss. Its been discussed thousands of times. It will need to be tuned on high octane (91+). Thats it.