I have a 1988 C4. After reading threads reguarding this spacer I wish I had not spent $93 on it. First let me say I never thought I was gonna get HP out of it. I did hope to gain some better gas mileage. Am I kidding myself or should I put this back in the box it came in and get my $93 so I can buy a tank of high octane gas ?

 

Trace the pattern and then get your money back...

People made those out of hardwood or plastics. Its a simple theory that has real gains...at the sacrifice of upper rpm range power. All it does is make each breath a little harder and further to pull inside. When you do this, the air charge accellerates as it responds to that increased suction. This shoots the air into the cylinder a bit faster so you feel some bump in low end power...BUT......that comes from a trade off at the top end. The harder it is for an engine to draw air in, the less efficient it becomes at high rpm so it falls on its face sooner, it just cannot breath well at that speed. Its like you running a marathon and only breathing thru your nose...cannot be done. You end up breathing thru the larger passage (mouth) to get more air when breathing hard and fast.
This ends up making the stock L98 range of 1500-5000 even tighter...more like 1200 to 4500.

Thats what most of these after-market "bolt-on" power adders do.....they just take power from one place and move it to another area of the rpm range. They don;t really add anything...they just move power around so it feels like there is more. Plus the placebo effect that has a direct relationship between the "noticable" power increase and the cost of the product.

 

I would rather have the top end and keep the car as intended. I live in Mesa AZ. Today it was 100 degrees and the first time I have turned on the A/C. The coolant temp climbed up to 240 degrees at traffic jam. I would rather never get it that hot so I lowered the window and turned the A/C off. It went down to 217 degrees. On the freeway it runs 210-220 with the A/C on. My oil temp is 240 degrees. Seems very high. What are your thoughts ? I am going to put 10W-30 synthetic Mobil 1 next oil change. Maybe sooner. It has Castrol 10W-30 oil right now. I am gonna return the spacer and go ahead and buy straight pipe. I will register the car in Prescott to avoid emissions.

 

That kind of heat is normal....yes, I am well aware of where you are...I lived in Gilbert for a number of yrs until 2007. Upgrade the cooling system with an all aluminum radiator, a 180 t-stat, and fans programmed to come on sooner. You;re still going to see 245 in rush hour but with these upgrades it'll take longer and cool down faster/easier.

I am now confused....
you call this item a "spacer"...where exactly does it go? under and behind the throttle body? A 1" thick block or plate thats bolted to the plenum?
Or is this some of the duct thats ahead of the throttle body?

Straight pipe...? what straight pipe?

We need to get on the same page with the termanology so you;re not getting the wrong information and end up making bad decisions based on that which was not understood..

BTW..
you can safely run 20/50wt in Phx in the summer. Your temp gauge will show the motor warmed up for a solid 4 months...with over 100 degrees showing. I used 20/50 summer and dropped to 10/40 winter (like there is winter in Phx)...In the misery they call Texsas...I run 5-30 winter and 10/40 summer.

 

I am sorry for being vague. When I said straight pipe I meant removing the catalytic converter just before the mufflers. I think it would be too loud if I opted for as I said straight pipe. I had to rethink that one. The throttle body spacer is just as you described. Bolted up behind the throttle body. I am going to return that expensive piece of aluminum. If you suggest 10W-40 for summer then thats what I will buy. I am hoping the synthetic will handle the ambient temps in the 100's better ! Unreal here in the desert. This L98 runs hotter than any engine I have ever owned. I recently purchased a Modine radiator and will put it in next week. I had the auxillary fan hooked up about 2 weeks ago. It comes on at 200 degrees along with the main fan. I did put a smooth coupler and a improved air foil in my throttle body as well as a K&N air filter with the air filter cover having two big holes for max air intake. I have read on here that a 52mm throttle body is a waste unless cams and intake runners are also upgraded. Until the engine fails I will keep it as is.

 

OK, got it..

a couple of suggestions....

there is no need to worry about removing the cats with a semi-stock motor. They do no harm to power production. When you do a whole system, then look for late model technology in new cats...there will be absolutely NO loss of power or performance and your resale value stays UP. I would not buy a car that had the cats stripped off because that is an immediate expense to ME to have the system brought back to the OEM standard so it will pass inspection and inspections are here to stay and they will get tougher and eventually in every state in the nation. Get used to that..its reality and an unfortunate necessity.

The other thing...the air-foil.I WOULD remove that asap. Those have been known to break and send pieces into the engine or stick in the butterfly and lock the throttle open. Not a good outcome either way...besides, those ARE truely a waste of money. They do nothing because they are not 'tuned' to that particular engine. Airflow is managed in many other places so that one spot in front of the butterfly makes no difference. Placebo if anything.
A $50 sugar pill.
If you want real results there you will have to buy a 52mm that is not a bad idea. If you get the plenum ported to accept the larger TB it does have benefits. Don;t go stupid big with a 58mm....most 'built' engines can;t make use of that much air. Anything bigger than a 52 will need a custom tune anyway.

Grinding out the plenum ports to match the 52 is a good Saturday job in the garage at home..pretty easy to match the port size with gaskets.

 

If you think a 52mm TB would be a sound upgrade when having the plenium ported I will price it out and see what it costs. I do want to thank you for taking the time to share your opinion with me.

 

i was of the impression that a bigger throttle body would add next to nothing on a near standard motor.

 

Correct. The difference is so small, any dyno measurement could be attributed to tolerance (error).

 

Scaryfast (Jon with a forged 383 LT1) put his car on a dyno after replacing his 52mm TB with a stock TB (because he was trying to lose some HP for his race class) and he gained HP. I can't remember the number but I think it was 8-10+. Maybe he will chime in...

The new TB's do look nice though.

 

Thats true.

BUT, if the plenum is port matched and the runners as I suggested, it WILL make a noticable difference and any subsequent mods will perform better, such as exhaust upgrades, injectors etc.

Just about every 52mm TB is an instant ($350) failure because people just bolt 'em up and expect results. Its NOT THAT EASY !

what good is a coffee can size TB if there is still a little 48mm hole a few mm behind the butterflys>???? None. This is why you MUST do some simple port matching (grinding about a lb of aluminum out of the plenum ports) to be able to utilize the 52mm enhanced airflow. Driver side plenum/TB port especially...40% blocked by casting.

Spend the afternoon with the die-grinder and THEN you will see results..

 

I think it's always assumed a 52mm would be ported matched on installation.

Hard to believe that's been the "issue" for all these years. Still don't believe port-matched 52mm is going to help stock $350 worth.