get more use out of the cold start valve........

fred cook · fred cook's Garage

When I built my SC engine into a 3.3SS, I was concerned about the larger engine possibly running lean at wide open throttle. After giving the matter some thought, I decided to find a way to activate the cold start valve at WOT to act as a "7th" injector. The end result was actually quite simple. I mounted a spring loaded contact switch on the throttle linkage so that it would be engaged at WOT and provide +12V to the CS valve. The extra fuel from the cold start valve is distributed to the 6 cylinders by way of the aluminum cold start manifold mounted inside the CIS air box. So now, when the throttle is wide open, the switch is engaged and the cold start valve opens. Now, at normal driving speeds, the CIS works normally, but at WOT, the air fuel mixture changes from around 14.5:1 down to about 13:1 or so. This way, when puttering around town the fuel mileage stays up and the car drives like normal. But, nail the throttle, and the engine pulls like a scalded cat all the way up to the ignition cutout set at 7500 rpms. Some pictures:

Reiver · 10-23-2015, 03:42 PM

Very innovative and a good idea for the lamda cars I'd guess.
I've a 930-10 euro SC and the AFR is controlled by the wur rather than your lambda as we just don't have one.
I use an onboard afr gauge to both tune and monitor.
I find the CIS is actually the 'leanest' in mid range and mine cruises at about 13.5, accelerates at about 13.8- 14 (a push but not wot) but feels good...now at wot I get about 12.3 and it jumps.
I believe the wur is more responsive and tunable than the lambda deal ( I had a 930-16 for comparison).
Your technique is pretty interesting.
Did you measure your ratios at cruise/accelerate/wot prior as I've always heard the lean was in the middle and not at wot. My afr observations support that with the CIS.

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by fred cook

When I built my SC engine into a 3.3SS, I was concerned about the larger engine possibly running lean at wide open throttle. After giving the matter some thought, I decided to find a way to activate the cold start valve at WOT to act as a "7th" injector. The end result was actually quite simple. I mounted a spring loaded contact switch on the throttle linkage so that it would be engaged at WOT and provide +12V to the CS valve. The extra fuel from the cold start valve is distributed to the 6 cylinders by way of the aluminum cold start manifold mounted inside the CIS air box. So now, when the throttle is wide open, the switch is engaged and the cold start valve opens. Now, at normal driving speeds, the CIS works normally, but at WOT, the air fuel mixture changes from around 14.5:1 down to about 13:1 or so. This way, when puttering around town the fuel mileage stays up and the car drives like normal. But, nail the throttle, and the engine pulls like a scalded cat all the way up to the ignition cutout set at 7500 rpms. Some pictures:

Fred,

Simply supplying 12 volts power to the CSV when the engine is warm won't activate it unless you provide a separate ground to by-pass the TTS (thermotime switch). Could you elaborate how you were able to make the CSV work as the 7th injector? Actually it is the 7th injector in a CIS. Thanks.

Tony

RarlyL8 · RarlyL8's Garage

This is not uncommonly done on boosted engines. You wire the CSV direct, independent of the daisy chain. There are also fuel enrichment systems that use a frequency valve to modulate pressure to the WUR.

RarlyL8 · RarlyL8's Garage

Nice simple solution for your increased capacity by the way, great that the distribution manifold feeds each cylinder.

fred cook · fred cook's Garage

I pulled a power lead to the CSV, ran a wire from the CSV ground side to the switch and from the other side of the switch to a ground. The power lead comes off one of the ignition relays so it can only be hot when the ignition is switched on. When the throttle is at the wide open state, it closes the spring loaded contact switch, makes the ground and activates the CSV. When not in a WOT state, the CSV works just like normal. I have an air fuel gauge mounted under the dash so that I can monitor the rich or lean condition that the engine is operating at. Pretty simple, really!

Reiver, I did not have the a/f gauge mounted prior to removing the engine. But, you are correct that it would have been nice to have the data for comparison purposes!

Reiver · 10-23-2015, 07:23 PM

With the CIS I can't imagine not having the AFR gauge on board....makes life simple.

That 3.3 SS must be a hoot. What HP/Torque are you making?

fred cook · fred cook's Garage

Quote:

Originally Posted by Reiver

With the CIS I can't imagine not having the AFR gauge on board....makes life simple.

That 3.3 SS must be a hoot. What HP/Torque are you making?

I haven't put it on a dyno yet, but the "seat of the pants" dyno says that it is quite a bit more than the 3.0 was making! The other thing that adds to the equation is that I have lightened the car down to about 2400 lbs! At this point, my best guess is about 260 - 275 hp on the ground.

Reiver · 10-24-2015, 08:54 AM

Quote:

Originally Posted by fred cook

I haven't put it on a dyno yet, but the "seat of the pants" dyno says that it is quite a bit more than the 3.0 was making! The other thing that adds to the equation is that I have lightened the car down to about 2400 lbs! At this point, my best guess is about 260 - 275 hp on the ground.

That is a really nice fig. Did you post a build thread on the 911 engine rebuild section?
I've a Euro '83 (204 hp stock) with SSI's and a Dansk pea shooter and am getting 225 out of it. Its been redone on the top end by a very good builder.
I've got the car down to 2480 with a full tank of gas.
250-275 would be a really nice spot.

Nice job to get that with a CIS in place.

Bob Kontak · Bob Kontak's Garage

Quote:

Originally Posted by RarlyL8

Nice simple solution for your increased capacity by the way...............

Always wondered if the CSV would be adequate for the extra rich needed for a nitrous charge. No clue and just thinking out loud.

MZ3 SBC · MZ3 SBC's Garage

I have a 79 930. I pulled theCSV and tested the resistance and found it to be around 3Ohms...so it is a low impedance...

I also read that the CSV is not designed to pulse and can easily be burned out.

However you seem to have had a different experience. Any long term updates?
Is it still working.

fred cook · fred cook's Garage

Quote:

Originally Posted by MZ3 SBC

I have a 79 930. I pulled theCSV and tested the resistance and found it to be around 3Ohms...so it is a low impedance...

I also read that the CSV is not designed to pulse and can easily be burned out.

However you seem to have had a different experience. Any long term updates?
Is it still working.

Yep, still working! I originally built the engine in 2013 (including CIS mods) so it has been a good 9 years. The trick here is that full throttle is used so seldom it doesn't seem to put much extra load on the CSV. The only thing I have had to fix since 2013 was to replace a damaged shift connector recently.