Rebuilding a 3 l row motor

GMR911 · 06:28 AM

Thinking about rebuilding my 930/03 , 78 3 L row motor that currently has ssi and stock exhaust, cis. This engine has large ports and intakes with 8.5 cr. Thinking about adding euro 3.0 L, 9.8 cr p & c, and a 964 cam grind, retaining cis and stock exhaust and single plug. What would be the approx hp figures for this configuration. Planning on running 93 octane gas. This is a street car , 77 chassis, 205 tires all around, carrera front brakes, stock rear brakes. Looking to maximize the efficiency of this motor, getting good midrange- hi end power for passing(maybe a better cam for midrange power?), retaing drivability. Any downfalls or things to be concerned with this configuration. Anyone have this motor configuration? Thanks Jerry

GMR911 · 10-19-2014, 03:47 PM

any thoughts on this build?

Reiver · 10-19-2014, 03:56 PM

I've an '83 row 930-10. That's basically what you are building minus the cam grind.
I've had that motor for 17k miles now with no issue. I did install a Carrera oil cooler/block off and fan in place of the worthless trombone as I live in Az and drive it dailey (100 plus ambient common). This set up keeps it cool....rarely see 205 degree oil temp...mostly 195- 200 on the hottest of days. I'd recommend that for the higher CR.
I have SSI's/dansk and guesstimate 220-225 HP. the car weighs 2460 with a full tank so it feels pretty nice at that HP. Mid range is strong from 3400 on up.
You should see more with that cam.

GMR911 · 10-19-2014, 05:01 PM

I have a 28 row fender cooler that keeps it pretty cool. Live in upstate NY so extreme heat s not an issue, extreme cold however is. Looking to get about 220-225 hp out of this build..so probably about right. Any problems with denotation running 9.8 cr?

Josh D · Josh D's Garage

One thing you'll need to keep an eye on is ignition timing.

I'm pulling this from memory, so it may not be totally accurate. I believe the RoW 930/10 has a fairly short timing curve. 5* BTDC at idle/25* BTDC @ 6K. That's 20* of mechanical advance.

Your '78 RoW may have more. My '80 RoW had 25* mech advance, so when set to 5* BTDC, I was getting 30* at 5K.

30* may or may not be too much advance for 9.8:1 on 93 octane where you live. It would be a problem here in AZ with our summer heat.

Reiver · 10-20-2014, 09:51 AM

Our max octane in Az is 91. I do use an octane booster and have had zero issues with detonation.
I think most of the horror stories about the row CR and breaking rings/detonation involved high engine temp and tracking the car and prob some det thrown in.
In your area that 28 row cooler ought to be fine.
I have an AFR guage for safety and run a tad rich too...that motor seems to like the fatter mix.

Josh D · Josh D's Garage

Quote:

Originally Posted by Reiver

Our max octane in Az is 91. I do use an octane booster and have had zero issues with detonation.
I think most of the horror stories about the row CR and breaking rings/detonation involved high engine temp and tracking the car and prob some det thrown in.
In your area that 28 row cooler ought to be fine.
I have an AFR guage for safety and run a tad rich too...that motor seems to like the fatter mix.

What do you have your ignition timing set at Pat?

Reiver · 10-20-2014, 01:35 PM

I have it per spec for the 930-10....25 deg adv @ 4000 thru 6000 rpm.

GMR911 · 10-20-2014, 05:05 PM

I think my distributor has 31 degrees of total advance, however the vacuum advance is not conected. The fellow who installed my motor said there was no port on the throttle body to hook it into. I have seen other row cars with the vacuum advance plugged like mine. Not sure if thats makes a differance.. especially with higher cr. Right now the car runs great as is

Reiver · 10-20-2014, 06:09 PM

I'd stick with the lower advance with the higher CR of 9.8-1. You don't want detonation with that CR.
If you limited your stock dizzy to 25 max it might impact your lower rpm range with a different advance sequence.
You may need to get it remapped/adjusted so it falls within the stock spec.....but I'm sure guys have done this so I'd check with a Porsche shop that does dizzy's for hot rodded flat six's...they'll give you the straight skinny.
I do know that the newer MSD ignition modules allow you to map your advance across the rpm range and that would also be a source for getting within spec.