300 HP Crossfire engine?

Reply Subscribe

Thread Tools

Search this Thread

Aug 7, 2019 | 10:58 AM

#21

Tom400CFI

Team Owner

Joined: Aug 2004

Posts: 21,543

Likes: 3,216

From: Park City Utah

Quote:

Originally Posted by 84 4+3

Otherwise regulated restriction is constant unless you're running enough fuel to build up tons of head... ie the return is too small for the flow rate returning.

^This^. I don't know why you were building too much pressure w/a 190 LPH pump. I used the Walbro 255 lph and it worked great on stock fuel lines and regulator.

Aug 7, 2019 | 05:53 PM

#22

GregMartin

Drifting

Joined: Jun 2018

Posts: 1,402

Likes: 287

From: Brisbane Australia

C4 of Year Finalist (performance mods) 2019

Quote:

Originally Posted by Tom400CFI

^This^. I don't know why you were building too much pressure w/a 190 LPH pump. I used the Walbro 255 lph and it worked great on stock fuel lines and regulator.

Yeah I bought the racetronix kit that was supposed to be for an 84. I never got to the bottom of it. I rebuilt the regulator a couple of times, I even zip tied the regulator spring so that it would support the diaphragm but not regulate, with the same results ie about 28psi.
The way I see it the are only three causes.
1) there is a blockage or kink in the return line.
2) the flow rate is too high for the return line
3) the pump is a higher flow rate than advertised (ie wrong one in the box).

if you had a 255 then 2 can’t be the case. You can calculate pressure in a length of pipe based on internal diameter, materials used, number of bends etc. but I haven’t attempted that. Just to cover off on this the breather is clear. I will get around to sorting this one day. I have a new return line and I can probably prove it’s state by disconnecting the return and directing it into a bucket.

Anyway I feel like I have hijacked the thread so apologies.

The short answer for 300ish HP is heads cam intake and probably injectors. You can check out what I did on my “84 journey“ thread and decided if it’s right for you.

Last edited by GregMartin; Aug 7, 2019 at 05:54 PM.

Aug 9, 2019 | 05:10 AM

#23

Polo Vert

Pro

Joined: Mar 2013

Posts: 698

Likes: 162

From: Huntington WV

150 shot of nitrous.....

Aug 9, 2019 | 05:23 AM

#24

GregMartin

Drifting

Joined: Jun 2018

Posts: 1,402

Likes: 287

From: Brisbane Australia

C4 of Year Finalist (performance mods) 2019

Quote:

Originally Posted by Polo Vert

150 shot of nitrous.....

Well they have forged pistons and rods so there is some strength in the bottom end

Aug 9, 2019 | 07:36 AM

#25

84 4+3

Le Mans Master

Joined: Aug 2017

Posts: 6,942

Likes: 1,490

From: New Jersey

Quote:

Originally Posted by GregMartin

Well they have forged pistons and rods so there is some strength in the bottom end

I've seen people do it, they hold. Just make sure it's a wet shot otherwise no matter the forging you'll have some see through pistons.

Aug 9, 2019 | 07:48 AM

#26

pacoW

Racer

Joined: Jul 2017

Posts: 422

Likes: 53

From: PA

a small bump in compression and headers should easily get most gen 1 or 2 SBC to 300hp, all else being equal. Check how much you can mill the heads down and change the gaskets out, might just be a trip to the machine shop and $150 bucks or so.

Aug 9, 2019 | 08:04 AM

#27

84 4+3

Le Mans Master

Joined: Aug 2017

Posts: 6,942

Likes: 1,490

From: New Jersey

Quote:

Originally Posted by pacoW

Not with the pathetic stock heads and cam. The late L98s were at 10.5:1 (1.5 higher than the l83) with a similar cam and were only around 250, with better heads. Needs a little more help.