CentralCoaster wrote:
I wired up a manual fan override switch on mine. It is a 2 pole switch that grounds out both fan relays. When the switch is off, they operate normally. A 2 pole switch is necessary to keep the electrical circuits separate.

I mostly use it after a run session, when the car is insanely hot, leave it idling and force both fans on to cool it down faster. The last thing you want to do in that situation is shut the car off right away, because the coolant still in the engine may sit there and absorb more heat until it boils. The fan will stay on but would only cool what's in the radiator.

Why would you need a separate relay? It would surprise me if there was feedback to the ECM to tell it the fan is running when it shouldn't be. I honestly don't know how the fans are controlled on yours though.

As for your radiator, it's probably cooling better, but your thermostat is just closing more to compensate. You're operating at the bottom end of the operating range, and the only way it's going to be less than that, is with a lower temp stat. I'm assuming you have the 180 now. The stat and the sensor are pretty far part in the chain of events that is your cooling system.

CentralCoaster wrote:
Did you guys have any issues with the Dewitt rubber pads? Mine is not completely isolated from the shroud, parts still come in contact. The radiator could've probably a 1/4" in height.

DrDyno wrote:

Thanks, Joel!

Found their Ad...

Once a year and only once a year do we have a forum sale. This is it.

1. You must order from our website, no phone orders.
2. You must use promo code Jan2015
3. Discount of 15% off anything in your shopping cart.
4. Sale ends January 26th, 2015
5. Allow 2-3 weeks after placing order before expediting

Any odd stuff, not on our website can be emailed to john@dewitts.com

tjpreul wrote:
I relocated mine to the front of the frame by the opti. This is where Procharger has you relocate it. It sits low so the hose in and out rest on the frame.

joeld wrote:
I've been checking for the last several weeks also, noticed tonight on that "other" forum they had the announcement.

Wasn't trying to bust into your thread, just wanted to let you know before I forgot.

Joel

joeld wrote:
DeWitt sale is on!
Ends Jan 26th
Promo code Jan 26th

I'm needing one also.

Joel

bogus wrote:
Another aspect of the temps... the insides of modern engines are a mishmash of alloys... iron, aluminum, copper, you name it.

Each metal heats and cools at different rates, and the temps established are perfectly safe because they are optimized to work with the different metals and keep emissions happy.

This is not a 1966 something with 12:1 compression, points and an appetite for 101 octane gas... this is a modern engine, with computer controls, and 10.5:1 compression with a much lower appetite for 93 octane.

In short, this is not a problem... this is normal.

Now, as for the radiator... I am a huge fan of the DeWitt unit... but keep the factory fans. They are super durable and easy to get parts for if one was to fail. If the DeWitt fan fails, you are boned until you can get the right Spall replacement part.

Which leads to thought number 2... Dave McClellen, former Corvette Chief Engineer, told me that his #1 mantra to Mosler (the guy in FL that builds a mid-engined thing with Corvette power), is to use as much OEM parts as you can. They are severely tested over long periods of time to maintain durability standards... most aftermarket places don't...

So those OEM fans you have are good for 100k or more miles. What durability tests do the Spall fans go through?

As for Dewitt rads? They are used in Corvette Racing, and, well, they are not a moving part. Good materials, good welding, should be a-ok. And in this case, to the best of my knowledge, not a single DeWitt rad has ever failed Corvette Racing, including the 24 hours of Daytona, the 12 hours of Sebring or the 24 Hours of LeMans.

Oh, and I have a Dewitt in my 92. I just got tired of buying cheap rads that died in 30k miles...

BillH wrote:

John, I build SBC's and I had the same thoughts when I first got my 92. So much so that I put in a manual switch to turn on one fan and used it.

...If it bothers you, you can put in a switch for $4 and run the fans. In traffic, it will take a few minutes for the temps to start dropping.

Spal fans won't help this at all at this point. A larger radiator MAY drop temps but only to 195 (that's what your thermostat opens at). Going to a lower temp than that may do nothing but build up crud in your engine.

TommyT-Bone wrote:

Guess it depends how you plan to mount your supercharger.

Matatk wrote:
1) In your previous post about mods you said with a flushed system your car rarely sees 205*.

There are much more highly modified cars than yours that do not require spal fans and an upgraded radiator. I'm sure the radiator is overkill for your application, but still a quality piece.

2) If you supercharge it, address the fans and a/c adaptation at that time.

Matatk wrote:
Why not just run the upgraded radiator, it will be more than sufficient. I would not want to worry about moving the accumulator/drier and custom a/c lines.

Matatk wrote:
Are you referring to the accumulator/drier?

Matatk wrote:
Do you have a mechanic's stethoscope? If not, you can buy one cheap at HF or the parts store.

Are you sure it's from under the hood? Sometimes noises can be hard to trace.

Possible causes already listed were injectors and rockers. If you do indeed find it is lifters, the LS7 lifters are a direct replacement and cost effective.

BillH wrote:
No drone.............no mufflers.

Matatk wrote:
As far as I know it's an LT4 thing, my exhaust is from a 96 LT4 and has it.

jonszr1 wrote:
the 96 cars had the rear crossover from the factory

Schrade wrote:
Who put on new exhaust, and got more drone inside than they were countin' on? Did you do anything (besides changing hardware) about it?

What did you do?

Matatk wrote:
Everything on that list are maintenance items. There is not one performance item on there. So just saying "I did a tune up and my performance is great" has nothing to do with adding performance.

I will not agree Bosch IIIs are an improvement just because of a Youtube video. Trust me, I have watched the same videos. I personally installed the Bosch III replacement injectors in my 89. The gas mileage went down. Many people have problems with BLMs (the fuel/air mix in basic terms) once they install them and scan the car. They are not designed for our cars. They are modified for them, but not originally intended that way. People tout them as the holy grail and it's just not true. You have better/more durable injectors in your 96 than came in the 89. I bet there is nothing wrong with them. Send them out to be cleaned/tested if you are that concerned. It's a 20 minute job to remove them and costs $100 for a rebuild.

...If Klyde got a huge improvement from o2 sensors and a fuel pressure regulator with injectors, then those components were faulty or failing on his car.

Just some food for thought.

Matthew

Matatk wrote:
Quote:

DrDyno wrote:
Thank you all for your suggestions. Air foil is out!
What I've decided on from your input and other C4 owners is the following:

1. Free flowing air filter cover Good
2. Bosch III Injectors from FIC Not necessary
3. Aeromotive adjustable fuel pressure regulator Good, but not necessary
4. New O2 sensors Good
5. 1.6 Roller Rockers (already installed) Good

Headers are a possibility for the future. I recognize I'm leaving HP on the table but I'd rather not for several reasons:
A. Cost Low cost vs HP gained
B. Heat Coated headers don't give off much heat
C. Constant maintenance Such as what?
D. Hard to reverse for eventual resale Not true

Again, many thanks for your input!

Matatk wrote:
Headers are reversible if you ever sell the car. There are kits that will adapt right up with your stock exhaust.

There is a guy on here Higgyburners who sells some nice CNC machined air filter covers if you are interested.

Matatk wrote:
...There is a guy on here Higgyburners who sells some nice CNC machined air filter covers if you are interested.

Matatk wrote:
Headers are reversible if you ever sell the car. There are kits that will adapt right up with your stock exhaust.

There is a guy on here Higgyburners who sells some nice CNC machined air filter covers if you are interested.

I have the bypass because it makes it easier to work on my car. The airfoil is not necessary. If you decide to put it in, make sure you loctite the screw in so it doesn't back out and get ingested in your engine (has happened before!).

Matatk wrote:
What are your goals? Are you spending money just to spend money? Repairs?

Best mod you can do now is headers IMHO. Being in Florida a Dewitt's rad is nice, figure $500 for the part. No real MAF mods to be done. Not sure what you mean by a short throw shifter for an automatic.

rklessdriver wrote:
Yes you should change the valve springs if you go to 1.6 rockers on an LT1. If not the factory LT1 springs are very close to coilbind and in some cases where factory tollerances stack up the wrong way, too close... not to mention depending on how many miles and how much hard use they have had, they could not have enough spring rate to control the valve train in all instances.

The factory LT4 springs actually set at a slightly higher seat height (1.780) via slightly different retainers and they are different wire dia.... thats how they get the extra lift out of them (up to .525) They are cheap, and solve all the potential problems of keeping the LT1 springs with 1.6 rockers.


$37.00 LT4 spring kit PN 12495494

$18.00 LT4 retainer kit PN 12495492

You need both.
Will

rklessdriver wrote:
We use Scorpion's rockers on most everything we build with stud mount rockers.

Top quality rocker arms and they are made in the USA right in Fla. Lifetime guarantee as well.

I have used that particular 3/8 stud narrow body self algining model a few times on Vortec, LT1 and LT4 engines. It's great for mild bolt on stuff and requires minor modifications to LT1 (remove drip tabs) and none for LT4's except new 3/8 studs for those with the 10mm studs....

For higher RPM or more serious engines your better off with a big body non-SA rocker, 7/16 studs, guide plates and hardened pushrods... but the big body rockers require more mods to make them fit under the centerbolt valve covers.

Will

BillH wrote:
Quote:

DrDyno wrote:
Quote:

rklessdriver wrote:
I would recommend Scorpion. Their narrow body self aligning rockers.

PN SCP1036BL.

$282.00 at Summit Racing.

Will

Thanks, Rkless! Those look like just what the doctor ordered! Have you used them or know someone who has?

If Will says "Use them", use them.

He's one of the 2 engine experts here.

rklessdriver wrote:
I would recommend Scorpion. Their narrow body self aligning rockers.

PN SCP1036BL.

$282.00 at Summit Racing.

Will

bogus wrote:
For the newer folks, one of the features that made C4guru.com special was the Tech Library. Well, that library still exists!

Check the left nav panel, and click on Tech Library! Take a scan.

They are all C4 related now, but I hope to get some more general and ones for other generations!