Gen 2 boost vs valve springs.

[Johnnie Phatt]

Educated people have said A gen 2 on pump gas should be held to 4 pounds of boost due to weak valve springs. I assume that means they won't close properly. Is is a simple matter of installing stronger springs to get the 8 pounds of boost available in a gen one motor or is it more complicated than that

 

[Mathewrussell52]

Educated people have said A gen 2 on pump gas should be held to 4 pounds of boost due to weak valve springs. I assume that means they won't close properly. Is is a simple matter of installing stronger springs to get the 8 pounds of boost available in a gen one motor or is it more complicated than that

You will run in to compression issues also. Stock gen 2 13-1. Titanium valves also so when you put valve springs on them don’t hold up very well also.

 

[c10]

Do it right or dont do it However a gen 2 with mild boost will still put a smile on your face , and make 240 rear wheel hp

 

[Johnnie Phatt]

some how I figured it would not be as easy as I had hoped But yes 240 RWHP is a lot of a lot

 

[Boosted Cycle Perf]

You will run in to compression issues also. Stock gen 2 13-1. Titanium valves also so when you put valve springs on them don’t hold up very well also.

It’s a 12.5:1cr.

4lbs of Boost is always advertised, but it’s usually 5-5.5psi when it’s all said and done. You never get exactly what spring pressure is rated for.

You can certainly get around the the high compression factor with enough octane, but the valve springs definitely are the biggest hold up. I want to say they’re like 20lb seat pressure or right around there.

This is one thing I’ll be playing with on the shop bike Lucy. I’ve always been curious how far they can be pushed. Typically when you get valve float you’ll see waves in the dyno readout, followed by a steady decline in power.

I’ve shown that on a stock gen 2 and “4psi” (5.5psi) you can make 280whp on e98. I’m going to try raising the boost to 7-7.5psi on Lucy on some gas station e85 and see if it makes 300hp or better. Lately the station by the shop has been pumping a consistent E75, so that should give me just enough head room with the stock injectors.

It will be exciting to see the results.

 

[michael parris heuberger]

It’s a 12.5:1cr.

4lbs of Boost is always advertised, but it’s usually 5-5.5psi when it’s all said and done. You never get exactly what spring pressure is rated for.

You can certainly get around the the high compression factor with enough octane, but the valve springs definitely are the biggest hold up. I want to say they’re like 20lb seat pressure or right around there.

This is one thing I’ll be playing with on the shop bike Lucy. I’ve always been curious how far they can be pushed. Typically when you get valve float you’ll see waves in the dyno readout, followed by a steady decline in power.

I’ve shown that on a stock gen 2 and “4psi” (5.5psi) you can make 280whp on e98. I’m going to try raising the boost to 7-7.5psi on Lucy on some gas station e85 and see if it makes 300hp or better. Lately the station by the shop has been pumping a consistent E75, so that should give me just enough head room with the stock injectors.

It will be exciting to see the results.

Hi. I am using PAC Racing valve springs Vance & Hines stainless + 1mm intake and V & H Inconal +1mm exhaust valves. I can not say what we will be running for boost, but it will a little over 4psi. LOL