TECH TALK - ask your technical car questions

[boganbusman]

Here's a stumper. My 1989 Ford Escort GT keeps losing oil pressure. It starts out at around 40 psi when it first turns over, but then drops off steadily as it runs until there is none at all. What, besides a bad oil pump, could be wrong?

Sounds like it could be your crank or cam bearings. Start by inspecting the cam bearings, because you can do that without pulling the motor out.

But first make sure it's not a faulty sender or oil pump.

[Grez~Supra_RZ-S]

I hope its not the crank, I had the same problem on my AW11 - it was crank case compression. I ended up selling the damned thing.

[chimpzrl]

[quote="boganbusman"]Sounds like it could be your crank or cam bearings.[quote]

How does that cause it to loose oil pressure? Does it start to go by the bearings or something?

[boganbusman]

How does that cause it to loose oil pressure? Does it start to go by the bearings or something?

Yep, that's right. As the bearings wear over time, the clearances become larger. Pressure will be fine when the oil is cold and thick, but as it heats up it will escape from the excessive clearances.

It's perfectly normal for bearings to wear, but it should be very gradual and a sudden loss of oil pressure means that something has probably gone wrong.

Possible causes for stuffed bearings:
- If the engine was rebuilt recently and not assembled correctly
- If you have been using the wrong grade of oil, causing oil starvation in certain conditions
- Or the engine might just be really knackered, but you haven't provided that much information

[chimpzrl]

Possible causes for stuffed bearings:
- If the engine was rebuilt recently and not assembled correctly
- Or the engine might just be really knackered, but you haven't provided that much information

You're a genius. The car only has 120k mi. but the thermostat went a couple of years ago. The car overheated massively, blew the head gasket and screwed the rings. We had new ones put in and that's when it started. We also put in new lifters as the old ones were worn. I assumed that the clicking from the cams was the new lifters not getting oil. Obviously it was actually the trashed bearings. Brilliant. My mechanic had the car for months and didn't figure that out.

P.S.: How hard is this to take care of?

[boganbusman]

You're a genius. The car only has 120k mi. but the thermostat went a couple of years ago. The car overheated massively, blew the head gasket and screwed the rings. We had new ones put in and that's when it started. We also put in new lifters as the old ones were worn. I assumed that the clicking from the cams was the new lifters not getting oil. Obviously it was actually the trashed bearings.

Whoaaa . . . hang on.

If the rings were done, then perhaps the bottom end was not re-assembled correctly. That could be the cause of the low oil pressure, and that would prevent oil from being pumped to the top of the engine where the cams are. So you might be right about the lifters not getting enough oil.

P.S.: How hard is this to take care of?

If you can do some work by yourself, pull the cams out and see if anything is wrong. If oil wasn't getting to the top of the motor, then you could have done some damage.

However, I have to recommend that you get the bottom-end checked as well, regardless of what you find in the head (because if the cam bearings are worn, you can't know if it was like that before or if it was caused by the low oil pressure).

This could cost you a fair bit in labour, so first double check that you haven't missed anything else. Hopefully it turns out to be something simple, otherwise . . . bad luck

[Strafer]

I have not checked out this thread before so i will just ask.

How come the car makes that distinctive sound, that "psssh"-sound.

[viper16]

if its turbocharged its either the BOV or Wastegate letting off boost

[boganbusman]

You can also have a blow-off valve on a supercharged car, but yeah that would probably be the sound you can hear.

A blow-off valve vents excess boost pressure whern the throttle is snapped shut (like when you change gears). It can be vented to the atmosphere or back into the intake, but in the latter case you usually can't hear any noise.

[jaycubzz]

Umm... not sure if there's a thread that deals with this or not, or even if it's technical or not, but here goes. Why do some drift cars have the graphics backwards on one side of the car? Is it purely for aesthetics or is it functional? thanks for helping my ignorance.

[xHaZxMaTx]

Every sticker gives you 1 HP.

[boganbusman]

Yeah it's just for aesthetics, nothing more to say really.

[Carcrazy]

Okay.. I just got my brother's 2002 Ford Escape, (he got a new SX4... the dumb*** turned down a Lancer X...) and this thing has major problems. It's acceleration is nothing compared to what it used to be, the tranny's got major problems, (will try re-setting the gear ratios eventually,) and it smells like some type of burning liquid if you try to push it to anything beyond normal use. It won't even reach 100MPH any more...

I'm planning on trying some things to lighten it, simple things like taking out the rear seat... just stuff like that.

Any other ideas on how I can help restore it on a limited budget... (like, VERY limited.)
Also, does anyone know anywhere I can good SUV parts? Thanks!

[viper16]

4 Wheel Parts good SUV stuff

[boganbusman]

Why would you bother trying to lighten it? It's never going to be fast if you don't have any money.
Just fix the damn thing, or sell it off and buy something decent.

If it accelerates poorly, check out the plugs, leads and dizzy/coil packs (I'm not sure what sort of ignition an Escape has) and replace as neccessary. This will usually sort out most poor-running issues, but we really need more details to diagnose the problem properly. Is it hard to start? Is the problem worse when it's cold? Does it misfire or stutter? More info.

About the tranny, check the fluid condition and change it if you need to, and don't forget the filter. If it's still bad, then there's not a lot you can do besides a rebuild/replacement. I'm not sure what you mean by "resetting the gear ratios".

With the burning, does it give off any smoke? The colour of the smoke could tell you what fliud it is. Check all your fluid levels to see if any are low and get under the car and see if anything is leaking.

The car isn't old, so it's probably worth trying to fix it.

[Grez~Supra_RZ-S]

Definitely dont bother stripping it of weight, and particularly dont bother with the rear bench. It will basically be made of two parts of foam, and will probably weigh 5lbs if youre lucky.

[setsunakute]

You can also have a blow-off valve on a supercharged car, but yeah that would probably be the sound you can hear.

A blow-off valve vents excess boost pressure whern the throttle is snapped shut (like when you change gears). It can be vented to the atmosphere or back into the intake, but in the latter case you usually can't hear any noise.

Or don't installed a BOV at all for better response/torque build-up when you get back onto the throttle (usually for larger turbines). Plus, I love the heavenly sound of compressor surge.
Of course, only if the engine can withstand it, and only if you're a competitive driver...

[Grez~Supra_RZ-S]

Not to burst your bubble, but compressor surge is the sound of a VERY poorly set-up car.

[boganbusman]

Indeed.
BOVs were invented for a reason, and the reason was not just to make a PSSSHHHT sound

[setsunakute]

Yeah yeah I know what a blow-off valve does. But compressor surge is sometimes unavoidable for cars with much larger turbines: the momentum of the more massive turbine shaft will cause it anyway. I'll cite one driver who uses compressor to his advantage: SuperGT driver Manabu Orido on his late 80-Supra. Constantly coming on and off of the throttle (such as for his drifting) doesn't allow enough time for the large single turbo to develop full boost. So, by using compressor surge, every time he gets back onto the throttle, the intake manifold is already flowing near-full boost pressure, therefore maximum torque when needed.

Of course, I did already say beforehand that this wasn't a good idea unless you are a competitive driver...

[Grez~Supra_RZ-S]

Im a VERY competitive driver, and no car Ive ever had would utilise compressor surge. If youve never seen it before, this is what 800bhp looks like:



This is my friends dad's newly rebuilt MKIV Supra. Look at the size of the turbo, and now guess how much surge it has?











Guessed yet?





None.

[Tunerfreak]

My head has all these crazy ideas floating around. I though I would bounce them off you guys.

You will have probably heard of I-VTEC (Intelligent VTEC, constantly variable cam timing) lets say we take a blacktop H22A1 and leave the cam lobe VTEC method as it is engaging at 5.2k rpm (Or whatever rpm is most efficient) and then attempt to integrate constantly variable cam timing on both cam gears powered by oil pressure activated by the rpm. Then say we run a second exhaust slightly larger and less restrictive with a constantly adjusting valve also opening with the rpm. By now we will need to remap the ECU to fine tune the fuel and now here where my plan unravels. For airflow for it to work efficiently I'm assuming you will most likely need an adjustable head intake also contentiously variable with the rpm, otherwise the car would run nasty at low end, or not make use of out new found top end adjustments. I'm wondering if there might be another oil pressure activated way to close the porting and expand it with rpms. Now lets say we crank the redline up over 9k instead of the measly 7.5k.

I am guessing none of all this will have any sort of gains worth the trouble and manufacturing required. The main thing is at low revs the engine will basically be a stock H22A sort of state and still be very economical, then as the boot is dropped the engine will cleverly pour on the little bits we manufactured to make it so the car is constantly at the complete optimal performance state for the rpm it happens to be at instead of just hitting VTEC once at a certain rpm.

Now lets say we want to go Forced Induction, Turbocharging to be specific, the fuel will need remapped I assume and the airflow may need adjusted, but we now are getting generous amount of power, as well as having all these little technology's to make sure all the power is optimized at every rpm.

I know its far fetched and unrealistic and most likely full of big flaws. But is it really going to make a significant affect than just engaging VTEC at 5.2 rpm?

Feel free to disagree, I'm just in it to learn.

[boganbusman]

You will have probably heard of I-VTEC (Intelligent VTEC, constantly variable cam timing) lets say we take a blacktop H22A1 and leave the cam lobe VTEC method as it is engaging at 5.2k rpm (Or whatever rpm is most efficient)

If it works anything like Toyota's VVTi, then the rpm when the timing kicks in is decided by the ECU after processing multiple inputs, (like rpm, throttle position, air temp, coolant temp, and so on). It won't always kick in at exactly 5200rpm. I don't think you wanted to know that, but anyway . . .

Then say we run a second exhaust slightly larger and less restrictive with a constantly adjusting valve also opening with the rpm . . . . . For airflow for it to work efficiently I'm assuming you will most likely need an adjustable head intake also contentiously variable with the rpm

Variable manifolds are old-school. Take my engine for an example. It has TVIS, which means that each cylinder has two intake runners, and one of them is closed off with a butterfly vavle. The idea is that a slightly restrictive intake gives better torque at lower rpm, and when you hit about 4000-and-something-rpm that valve opens, which is supposedly better for top end power. It works, sure, but Toyota soon abandoned TVIS and went with single smaller runners (you might have heard the names bigport and smallport?). A single smallport gives better air velocity, and works well at any engine speed.
If you're going to spend money trying to fab an intake, go for individual throttle bodies with velocity stacks and a nice large airbox. Best solution for any engine.

As for the exhaust, some decent tuned-length extractors with an appropriate diameter is all you need. A variable system would only create turbulence and restriction.

Now lets say we want to go Forced Induction, Turbocharging to be specific, the fuel will need remapped I assume

Ya, fuel map will always need to be optimized whenever you change the setup.

I am guessing none of all this will have any sort of gains worth the trouble and manufacturing required.

Indeed. Don't make things too complicated, and spend the money you saved on petrol

This is just general info, because I don't know much about Honduhs, but I hope it helps a bit.

[Cipher]

The R33 cOMES STOCK WITH HOW MANY HORSEPOWER.??


i was wondering because i dont have time to dyno my car,and i have already tuned it.
just wondering how much stock?

by the way its a GTR

[xHaZxMaTx]

While the published figures from Nissan were as quoted above, practical tests showed the car had a factory power output of closer to 330 ps (325 hp) at the flywheel. The lower published figure was Nissan's response to the need to abide by a gentleman's agreement between the Japanese auto manufacturers not to release a car to the public exceeding 280 ps (276 hp) of power output.