v8 RPM and temp questions & oil pressure

Scot · 07-12-2002, 01:58 PM

I just got the V8 (350 with about 300hp) from Don in Jacksonville florida. It is in very nice shape, and the engine sounds awesome! (rumble).

Anyway.... he has the Tach set at about 5800rpm for the redline.? It seems to be set up with more upperrange power and less low end torque... shouldn't it spin a good bit higher than 5800rpm?

and...... the temp guage in 86F ran up to about 210 or so coming through some 30mph traffic.... what is the max i would like to see there (just so I know what to look for)

next.... oil pressure guage.... this is the only car that i own that has one... what is good? I think it was about 40psi moving through traffic at 40mph in 4th gear.

thanks

so far so good.

Scot

Brad Roberts · 07-12-2002, 02:21 PM

Most early 90's Vettes and Z's ran around 220 all the time. All these cars have aluminum heads and intake.

I wouldnt run it over 220 for any length of time.

5800 does sound low.. maybe it heats up if you run it past that.

I would need the cam specs to tell you a different rev limit along with the valve sizes and port sizes.

Living in FL. You will be replacing the radiator with a proven setup from a conversion house.

How do you like that armrest.. I mean water pump ?

B

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Rule of thumb for oil pressure: You want at least 10 PSI per 1000 RPM.

As long as you don't go "too high" (what, 150 PSI cold and 80 PSI warm?) anything above that is great. If you get much below that, particularly at anything other than idle, start looking for a place to rebuild the motor.

--DD

JayDarden · 07-12-2002, 03:18 PM

My V8 powered 914 still pulls at 6,000 but I set my shift light to come on at 4k because it keeps me from racking up the "reckless" driving tickets. If I feel like making a run I set it to somewhere around 5,800 and hold it down for a second after it lights. I would be surprised if you could hold your foot in it past 4k 'till you get some seat time. Honestly I can drive for days without reving past 3 grand.

The general rule is 1 psi per hundred rpm. After things get good and hot my car runs 8 psi at idle, and 40 psi at 4k. A heavy pump just wastes hp, all you need is some flow.

Check out the Yahoo Porchev group, they can answer all your questions.

John2kx · John2kx's Garage

Scot,

Glad to hear you received your new car in one piece!

As far as revving it over XXXX rpm, you would need to know the components used during engine assembly at a miniumum to make this call. I'd shift in the 5500-5800 range to be on the safe side. If you are expecting to shift at 7000, get out the checkbook, this is gonna cost you unless the PO has purchased the right parts.

Water temp.: 220 is on the high side but I have owned a few factory cars (vettes) that lived there per design. The guys I know with v8 914s are running 180-190 F in summer traffic but this depends on how the car was built. The Renegade radiator is key in keeping the 914 v8 cool. Also, how the cooling lines are routed play a factor here as well. The front radiator/rear v8 can be made to opearate well in a 914.

As Jay mentioned, checkout the Porschev Yahoo BBS. You've got allot to learn and "it's in there".

I seem to remember a pic of your cars interior that showed a torpedo tube between the front seats and appears to be a custom installation. Find out what you've got and ask away at Porschev.

John

Scot · 07-12-2002, 05:55 PM

I have a S2000 that pulls til 9000rpm. I like RPM's.

Anyway.... this thing seems like it has some balls for sure....

Quote:

Originally posted by JayDarden
I would be surprised if you could hold your foot in it past 4k 'till you get some seat time. Honestly I can drive for days without reving past 3 grand.

The general rule is 1 psi per hundred rpm. After things get good and hot my car runs 8 psi at idle, and 40 psi at 4k. A heavy pump just wastes hp, all you need is some flow.

Check out the Yahoo Porchev group, they can answer all your questions.

Scot · 07-12-2002, 05:57 PM

I am in harrisburg, pa.... but it gets warm here.... it has a fairly large radiator with some nice pretty blue lines running to the engine.... i just wanted to make sure that i wasn't going to cook the thing on it's first day of use by me.

Ya, that armrest/ water pump / torpedo (as someone else called it) is a bit odd... it gets hot too, which makes the carpet on it want to peal off.

O well... still a fun(ny) car.

Scot

Quote:

Originally posted by BRM9148

Living in FL. You will be replacing the radiator with a proven setup from a conversion house.

How do you like that armrest.. I mean water pump ?

B

rich · rich's Garage

When you recover from the purchase check out the Renagade water pump. I was at there shop and looked things over. There parts are top notch. Then you can get rid of the torpedo.

clubracr · 07-13-2002, 06:28 PM

I don't have any experience with the V8 914s but a friend of mine is building a Model A street rod with a SB chevy motor. He purchased an adapter that fits over the water outlets and raises the pump vertically about 6 inches. Then a 6 cylinder chevy water pump bolts to the adapter. Somewhat more compact the V8 pump. Cooling has not been a problem with the car with this setup. I don't know where he got it. Check out the street rod sites if interested.

sammyg2 · 11:01 AM

Chebbies don't build as much oil pressure as most Porsche engines, but they don't need to. I figure that it should have at least 10 psi at idle, 60 psi when cold and running over 3000 rpm, and around 40 psi when warm.

My V8 car ran around 205 degrees when driven normally and it got up to around 210 when driven real hard. I had it up well over 230 a couple times at the track (even boiled it over once), but that was before I installed the Griffin aluminium radiator. After that it never got too hot.
Make sure you have plenty of good antifreeze in there, it helps prevent boil over as well as provide corrosion resistance.

As far as rpm, a normal stock 350 chebbie will fall off on the power curve at around 5000, if is has an "RV" cam that will bump it up to around 5300, but to go over that you will have to have a hotter cam as well as a higher rpm intake manifold.
Another limiting factor is the heads. The 194 heads (1.94" intake valves, 1.5" exhaust) will not spin as high as the 202 heads (2.02" intake, 1.6" ex.)

Most high performance street maifolds are a compromise and don't really go much over 6000 well. If yours is one that has a gap between the runnners and plenum then it will do it easily. Most hp parts suppliers/manufacturers exaggerate the real rpm range of their products.

A chebbie with a stock lower end (4 bolt) will spin to 6500 occasionally without breaking, but that is pushing it. I would not do it on purpose. IMO 6000 should be the max rpm as a general rule, inless it is a purpose built engine. A 2 bolt main block will not take as much rpm as a 4 bolt.