How much Boost should I have on a stock 87'?

[jwrape]

I know this sounds stupid, but I am boosting up to 12psi and I was under the impression that 87's with stock ECU's stop at 8psi or something like that. I have a 89 ECU I haven't installed yet but just started boosting yesterday after 300 miles and a re-torque of the head and saw it going up to 12 psi.... It doesn't seem to REALLY feel a whole lot more than say 8 psi on the gauge but the gauge jumps up there and can stay there if I keep my foot in it, but I am still scared of hurting the new motor so I don't stay in it long and I have a very slight surging issue throughout the rpms so I don't want to hang onto 12psi with a possibly lean condition. But I was just curious how a 87' Stock ECU'd car can pull 12 psi without even a Boost adjuster valve or anything.

[scott87star]

7.5 is max at which point the waste gate opens. So, faulty waste gate most likely. What gauge are you looking at? The stock one in the middle of the instrument cluster is not actually reading pressure so it could be off.

 

Scott

[jwrape]

7.5 is max at which point the waste gate opens. So, faulty waste gate most likely. What gauge are you looking at? The stock one in the middle of the instrument cluster is not actually reading pressure so it could be off.

 

Scott

Yea, the stock gauge. I knew it could be off but not that much... But it doesn stop at 12psi... Hmmmm

 

I need to drop that 89 ECu in there. It's plug and play isn't it? No Mods needed to run a 89 ECU???

Edited March 12, 2010 by jwrape

[Indiana]

Stock gauge is a feedback calculation not a pressure reading. I'd not change the ECU you'll not see any difference. An ECU has nothing to do with boost control as that's a mechanical device that is forced to open with pressure. The injectors are the same, the MAF is the same, the pump, engine its all the same. There's this assumed boost limit and where did it get an input that could tell it to cut fuel? Having plugs foul out and cause misfires isn't a fuel cut. Having the fuel too rich from non OEM regulators isn't ECU related. The timing curve is controlled by the distributor and modified by the IGNITOR not the ECU if there is knock. An 87 ECU uses regular unleaded gas and yes its advertised boost level is different by a little, the 88/89 added in that solenoid and had a circuit in the ignitor to lower boost by a few psi if the knock sensor went off from not using premium fuel. People take off that solenoid and use a MBC and most run premium fuel anyway. Changing the 87 ECU to an 88/89 imo is a waste of time. How about you use the correct spark plugs instead. You could swap wastegate actuators and hook that back up and you'd have the same "stock" boost pressure the 88/89 had in your 87 with its other 87 parts all left alone. With ignition timing maps pulled back for higher boost levels on stand alone ECUs, using a non intercooled distributor will result in lower total ignition timing by a few degrees with your stock ECU. Max power is achieved around 12ATDC for any motor*. I didn't invent or come up with these things its just the facts I'm only posting what I have found and I know what using those plugs do and the difference they make.

 

1984 distributor, mechanical adv.

0 degrees @ 600rpms

6.5 @ 1150rpms

12.5 @ 2500

 

1986

non intercooled

0 @ 1200

13 @ 2300

25 @ 5000

intercooled(same through 89)

0 @ 1200

10 @ 2000

33 @ 6000

 

The weights are different, if you buy a distributor or are unsure what yours is, check out the part # and look it up

http://www.b2600turbo.com/factory_part_numbers.htm

 

Spark plugs changed over the years, the type of plug in the late models changed and the alternate plug was used in the lower boost level non intercooled fuel system motors.

1988

http://www.b2600turbo.com/Spark%20Plugs.htm

 

 

 

 

*http://www.kb-silvolite.com/article.php?action=read&A_id=39

[jwrape]

So I should be using NGK BPR7ES ?

 

I really don't know what I bought to put in it. I will have to take a look.

[Indiana]

No, I think that's the big problem and has been. BUR7EA-11 those are anti fouling type plugs that won't misfire. You can get them at Napa, the part number is 7031 and they are around 2.75 each.