My LS1 Conversion 911

[Yan2947]

Talking to the guy who programmed my computer at Jim's Performance - my fans should go on at 197F and off at 195F. He said that he programs the computers much less then GM and that GM sets them around or above 215F to go on. I think you are going to be fine. I would wait for the hot days and see where you sit.

[shanghai_todd]

Agree, I am over engineering it and setting my 200F max limit to high, reality of living in Florida and where the radiator sits 210F will make due.

Drove the car for over 3 hours today within the city with several stops and did not see anything beyond 212F.

Something that still puzzles me is why my car can idle in the garage with no air flow and maintain 192~194 with the fans cycling every 10 or 15 seconds. Once on the highway cruzing @ 65mph in 5th gear and no load the temp will raise to 205~208F, I would have suspected that the temp would go down

I am also 2nd guessing my 3rd X-over muffler as being overkill and causing some exhaust restriction and back pressure into the heads wich could be causing the higher temps.

Other issue with the X-over muffler is that it is producing heat soak in the rear and is only about 1.5" away from the crank pulley. Already had 1 alternator belt turn gummy and start squealing. Replaced belt after less than 5 miles and OK for now.

Taking the car into the shop tomorrow and plan to just use the side mufflers and a diffused exhaust tips.

Originally Posted by Yan2947

Talking to the guy who programmed my computer at Jim's Performance - my fans should go on at 197F and off at 195F. He said that he programs the computers much less then GM and that GM sets them around or above 215F to go on. I think you are going to be fine. I would wait for the hot days and see where you sit.

[Yan2947]

Once you start pushing the car, the horsepower kicks in causing more heat even though the air flow is now cooling it. Take it to a drag strip and do some 1/4 mile runs and I'm sure you temp will rise high above 220F.

I am going to put a cross over pipe on my exhaust. Not the cross over muffler but just the pipe along with the 2 regular mufflers. First I need to get the darn thing running! Just got my tach back and along with the fuel/coolant temp gauge. Christmas is coming!

[Yan2947]

And where is the new video of the car flat lining it in on the streets of Miami! Lets see some burn out video!

[911t Fanatic]

I have just started reading your thread and have had many ls1's. Great engine and very reliable. However, placing the radiator in the back is a problem. Idle in the garage lets the fans do thier job. Going down the road, the outside air will actually start pulling the air away from the fans. Believe me. I had the same situation when i removed the original belt fan and installed electric fans. I know you think it doesnt relate to what you have but i have seen other ls porsche conversions with the radiator in front which was better not only for cross flow but the added lenght of hose helped immensely. They have turbos mounted in the rear of front engine mount cars and the added length of hose going back to the engine even did away with a subcooler. something to think about. try driving till the temps go up at different speeds for varied amounts of times and stop. Watch the temp fo down. Logic would make you think that after driving and then stopping they would keep climbing. I think they will go down. let me know what happens. You have the best of both worlds, with your conversion. Good luck!g\

[shanghai_todd]

Getting some great feedback on this and appreciate everyone's comments, I did some more testing yesterday and here are the results:

50/50 DI Water + Dexcool + 160 T-stat
First test: 30min idle time while sitting in the garage with no incoming air (Outside Temp 70F). Fan's pulling in air and pushing over the intake and engine. Temp range after heated up was 186~190F. Average coolant temp @ 188F.

After 30min of idle time I did my last minute Christmas shopping and drove the car around town for +2hr, as you can imagine traffic was horrible but I did get a couple of open stretches and back roads where I could nail down the pedal.

During this time the engine did not exceed 220F and averaged 210F while cruzing. While in traffic at a light the temps would begin to fall under 200F.

Oil temp once engine is heat soaked is around 245F.

Overall the system is maintaining steady temps and is able to suck out the heat from the radiator when needed.

I will keep the current mixture till summer time and see how it holds up in 98F Florida weather.

[scott.k]

ls1 is a great choice of engine for a v8 swap. Nice work

[shanghai_todd]

Week 2 and around 100 miles of testing and under "normal" driving conditions the temp range is 210~220F with weather conditions in the 60's. Performance is unbelievable and so smooth when the power comes on, like a Porsche on steroids..

Under harder driving conditions and higher RPM's the temp does reach 230F which I am not to happy about. The radiator is completely capable of drawing out the heat but I talked myself into this being a capacity issue. The system only holds about 1.7~2 gallons which from what I have seen is half the recommended fluid. Larger jugs on the radiator and slightly thicker would probably have been better.

Still on the fence what I want to do and plan to ride it out and enjoy having it back on the road. Just need to keep an eye on the gauge and Florida's summer weather.

Once I hit the 500 mile marker I plan to get her Dyno tunned and tweak the 5.7L PCM to the 6.0 Vette motor I have, this should free up another 30~50hp

BTW, had the tires break lose in 3rd gear.. First time my Porsche has ever did this and I have 12" rims sitting on 305's..

[petevb]

Originally Posted by shanghai_todd

Something that still puzzles me is why my car can idle in the garage with no air flow and maintain 192~194 with the fans cycling every 10 or 15 seconds. Once on the highway cruzing @ 65mph in 5th gear and no load the temp will raise to 205~208F, I would have suspected that the temp would go down

Something doesn't sound right. What rpm do you have at idle and at cruse speed?

Sounds like a flow issue to me, either airflow or a restriction in the coolant flow. I suspect I don't have a ton more core area than you, but my temps go down at freeway speeds to ~165 if I remember. I notice I have a significantly larger cooling pipe cross-section... Might be something to look at.

[Outlaw 911]

Hi Todd-

Great 911 LS1 build - fun to watch from the side lines.

Please remember the following is must my observations and opinion - but I did stay at a Holiday Inn last night. Couple of things to consider for the cooling issues:

1 Radiators are not designed to be layed flat - like in your current configuration - any air in your system is either sitting in the side tanks or the tube/finned area- any air in the tanks or tube/finned area will lower effeciency considerably.

Suggestion - tilt the radiator with inlet higher than the exit - like it was designed to do. Wont take much of tilt, but get the air to the top.

2 Once a 911 is rolling down the highway the area above the engine grill or whale tail is a low pressure area - meaning that air will be drawn up from the bottom of the engine compartment through the radiator. Think air plane wing - the rear of a 911, even with a tail is sloped like a wing and the trailing area - the roof, back glass and engine lid are in low pressure zone. In a 911 with the air cooled engine -the engine cooling fan pulls a ton of air through the grill and this is not an isssue. Look at mid 80's 935's , they raised the back of the 911 body way up in the air and ducted air to the engine fan from the side of the body to help elminate this low pressure area.

Hence the reason when sitting still, your fans can push air through the radiator, but once moving they are fighting the native aero of the 911. I would guess there is very limited air moving through your radiator at speed - hence the reason you run warm on the high way, but cool at idle.

Suggestion - 1) install 2 large Subaru WRX STI style scopes on the top of your grilled area of your tail to grab air coming off the back window (this will give the air in inlet via high pressure) and 2) then vent the tail/lid with very large holes/vents above the rear center reflector below the trailing edge of your tail - - so you have an exit (even more important than the entry) in a low pressure area - sucking the air through the radiator.

3 If the raditor is the highest point in the cooling system - that is not good - get an expansion tank - not a surge tank - and place it a few inches higher than the high point in your cooling system....get the air to to the tank and out of the radiator.

Hope this helps.

Outlaw 911

[Yan2947]

I have been thinking about what Outlaw 911 added about the scoop. I've attached 2 photos from BR Racings GT3. Anyone know how to get one of those scoops?

[shanghai_todd]

Been sometime since my last update so figured I would share the latest on my LS2 conversion.

After several months of trial and error and testing the rear radiator I decided to revert back to a RH front mount radiator and gas tank. Lucky for me a fellow Pelican Mkingham lives locally and had a tank @ the right price to help influence my decision, the guys at RH were also a great help.

Regarding the cooling ability of the rear mounted radiator it did the job and handled the Florida heat under normal driving conditions but I was not 100% satisfied when the engine was heat soaked and driven hard. The issue was not so much temperature related as max temp would achieve 235F and would drop to 215 quickly once in idle. Concern I was having was IAT and heat that was being spread across the intake manifold and robbing performance. IAT would reach as high as 180F. This could have been countered by adding a heat shield and re-routing the intake.

Now for the new setup max temp has not exceeded 200F and runs between 192~198F with IAT around 98F. To help facilitate this I have added 2 huge K&N filters in replacement of the smaller cone. Gas gtank was wrapped in DEI tunnel shield and I used the leftover shield to create a underbelly pan that extends beyond the tank and around the fuel pump. Great product, easy to work with and very happy with the results.

[shanghai_todd]

BTW, you can not see from the picture but the radiator lines from the front to the back tuck under my rockers. With my 993 body kit there is a 2" pocket

[LvSteveH]

Looks great Todd. Glad it's working well for you.

The DEI floor and tunnel shield is nice stuff, we use quite a bit of it. Another product that a customer turned us onto is called Armaflex. It's available in sheet form and is 1/2" thick closed cell foam with an adhesive back. It's also moisture resistant so it's great for automotive use.

A lot of people have run the coolant hose through the front crossmember instead of under it. I haven't heard of any issues. We typically weld in aluminum 1.25" stubs so the hose connects on each side of the crossmember. It looks nice and is easy to do. Just make sure you have the angles right the first time. It's a real pain to fix if they are welded in wrong. If done properly I doubt there would be an issue just running the hose right through the web of the crossmember, but you may sleep better at night with it welded.

[MarKoBrow]

Steve,
I saw your conversion and based on your last post here I have come to the conclusion, you are a class act.
Todd car looks great, do you have any room in the trunk for luggage.
I am still toying with either putting an STI or an LS6 powerplant in a shell I bought a few years back.

[shanghai_todd]

Been driving the car daily now with temps in Florida reaching well over 90 and no issues at all with cooling or reliability. The power is great and raced a worthy opponent yesterday, 2009~2010 Carrera S.. Although I was not able to pass him I was glued to his rear bumper from 20~100mph which was impressive.

The car is a mid-range monster with the 915 tranny and I foresee a 930 tranz withing 2 years and before any huge power adders.

I am guessing my HP is around 375~390Hp but still could benefit +40Hp from removing the 2 side mufflers and a Dyno tune.

[nippy]

Very nice,Im in St Pete,love to see it in person sometimes.Cars and coffe this weekend at Dupont if you can make it.

[shanghai_todd]

BTW anyone wanting to purchase my old radiator setup I am selling for $350 and will include flex hoses. Been sitting in the garage since I removed

[nippy]

Whats up with this project?

[Mike Hall]

If it was possible to build a set of 180deg headers to fit a 911, I would have also thought about doing this conversion. A LS motor with 180deg headers sounds wicked.

MIke