[zildjian4life218]

Well I got a parts car last weekend for my 1986 Olds Cutlass. It was a completely rotted out 87 monte carlo which happened to have a brand new gas tank .
I have been wanting to ditch the mechanical fuel pump in my cutlass for awhile and figure this is a good time to have this take ready and just be able to do the old switcharoo and run a 12v connection to it. What are the pros and cons of both the inline and intank. I planned on pulling the old line out (its 5/16" i believe?) and replacing it with a 3/8" feed and 5/16" return. Return line is leaking currently so im actually using the tank vent line that used to go to the charcoal canister for my return off of the mechanical pump. I will obviously be running a return style fuel system with a good regulator up front. I just want a nudge in the right direction. I bought a book from fivesecondsflat.com that had a section on fuel system design which I will read through before I make any purchases or decision. So what do you guys like. What have you had good luck with. Engine should be making about 400hp on a good day but I will have it ran on the dyno in a month or so when its back from the machine shop.

Thanks!
Shane

[35WINDOW]

I think it's a preference kinda thing-on the one hand, an in-Tank Pump is cooled by the Fuel (but can be a pain to change), and, it can be quieter (because the fuel insulates the sound), while an in-line has to be a good one if you are not putting it below the fuel line (but it is generally a lot easier to change)-

I'm a in-line kinda guy, and I rubber mounted my Pump and put it in insulated clamps-if you decide to go in-line, go with a good one (Aeromotive, Weldon, Magna, BG, etc.)-

[ap72]

there are a couple of reasons to go inline but generally intank is better.

if your in-tank pump cannot meet the demand you may need to go inline or get a different tank to run an in-tank pump. Also, installing an inline pump is a LOT easier, though if you have an access panel an intank pump isn't such a big deal.

If you can always run in-tank.

[zildjian4life218]

have any of you guys used those "universal" in tank pumps?

[zildjian4life218]

using a universal will probably open me up to more options rather than just whatever pump would fit into a monte carlo.

[ap72]

Originally Posted by zildjian4life218

using a universal will probably open me up to more options rather than just whatever pump would fit into a monte carlo.

The stock pump from a monte carlo may be more than adequate for 400hp. Pressure has a lot to do with it, also the BSFC of the engine.

[zildjian4life218]

Originally Posted by ap72

The stock pump from a monte carlo may be more than adequate for 400hp. Pressure has a lot to do with it, also the BSFC of the engine.

NA engines are around .4-.5 bsfc right? Most pumps I have seen are EFI which idk if there are any disadvantages to running that high pressure pump to the regulator then just let it run back the return. The calculator on walbro said 200 lph should be good for 400hp at .5 bsfc so even if I stepped up to a 255 lph which is a popular size I should be okay since I will have that return

[ap72]

Originally Posted by zildjian4life218

NA engines are around .4-.5 bsfc right? Most pumps I have seen are EFI which idk if there are any disadvantages to running that high pressure pump to the regulator then just let it run back the return. The calculator on walbro said 200 lph should be good for 400hp at .5 bsfc so even if I stepped up to a 255 lph which is a popular size I should be okay since I will have that return

200lph and 255lph at what pressure? and there is generally no problem with running an efi pump with a low pressure regulator, provided your return line is adequate.

[E.Furgal]

Originally Posted by ap72

The stock pump from a monte carlo may be more than adequate for 400hp. Pressure has a lot to do with it, also the BSFC of the engine.

#1 the monty would have been carb's so no intank pump
#2 I want to see you install a chevy fuel pump on an olds , and a factory mechanical chevy pump won't feed a 400hp engine even IF the cutlass has a small block chevy under the hood.

[E.Furgal]

if you want an inline pump. go buy a grand national/t-type tank/pump/sender

[zildjian4life218]

Originally Posted by E.Furgal

#1 the monty would have been carb's so no intank pump
#2 I want to see you install a chevy fuel pump on an olds , and a factory mechanical chevy pump won't feed a 400hp engine even IF the cutlass has a small block chevy under the hood.

#1 the car was originally from the factory a V6 TBI (computer controlled carb) so it does have an intank pump. I have pulled the pickup out myself and seen it. Unless the previous owner did something strange in the tank.

#2 Im assuming your talking about electric pumps becasue that is what this post relates to so what is the big deal about installing a chevy pump in an olds. Do you think there is going to be some strange black magic between the two.

Its getting a 400hp engine hence the after I get it back from the machine shop and run it on the dyno so idk why your hung up on the fact that a stock mechanical pump wont feed a 400hp engine. I think most people realize that. Hence why I am moving to an electric pump. Did you not read my first post?

And

Originally Posted by E.FURGAL

if you want an inline pump. go buy a grand national/t-type tank/pump/sender

So your suggestion for if I wanted an inline pump which I don't is to go get a grand nation tank/pump/sender......sure sounds like an intake pump to me and probably rather pricey and hard to get ahold of. Especially if I can just get an aftermarket universal pump and pickup. for around $150. I don't understand your reply post. It doesn't seem to relate to my question or provide any supportive input.

[E.Furgal]

the gn pump is in tank.. not inline.. my bad.. used wrong word
the computer controlled carb has a mechanical pump.. tbi isn't a carb
the tbi runs at 15-19psi..
the buick runs at 45-60psi
a carb 5-7psi..
the tbi pump didn't move much volume of fuel.. as the v6 tbi didn't need much..
the s.e.f.i. in the t-type and g.n. moved tons of fuel when compaired to a tbi pump..
if your goal is to run a carb on your olds, you'll need a return line and a fuel pressure regulator.. to use the tbi pump..
if you plan on efi down the road.. any multi port efi will need more psi than that tbi pump will put out..


note... a deadhead fuel regulator will kill any electric pump.. you must use a return style..
new cars don't have a return line because they use a regulator/bypass at the tank..
only thing that cools the pump is fuel flowing throw it..

[vinniekq2]

If I used an electric pump,I do not,I would use an after market in tank pump.I would run 1/2 inch line to the engine and w/e return line is required.I would use a pump that supports 500 plus horse power for a 400 hp engine.use a regulator

[1Gary]

While there are in-line pumps that met the pressure requirements,many fail in volume. The last in-tank pump I installed was for a EFI/CPI Delco in-tank.We had for yrs suggested Delco as a OEM replacement pump.After getting all back together I found the specs for the Delco had changed in that it didn't have the OEM pressure specs.One of the main reasons for swapping out the pump is it had one of those cheap Airtex pumps in it that are junk.Kind of ticked off I got ahold of Delco's tech dept.They told me the pressure isn't as important as the volume.Truth is it sounded like Delco found a crossover pump and swapped it in the part number I wanted to save money.Yet you still spend the money for the Delco brand name.On the other hand Delphi still sells the OEM pressure and volume.So apart of this post is about brand names and really looking at the current specs.But stay miles away from off brands because they never last long.The aftermarket hot rod in-line pumps that have both the volume and the pressure are expensive.

The other thing is while using a in-line pump you should not be trying to do so by leaving a dead in-tank pump pulling the fuel through it.FP's like to push fuel better than to draw fuel to it.But I am going to contradict that last sentence.We found one pick-up that is a OEM mechanical pumped return line style in a 1985 Astro which is nice because it has all the lines and a sock filter on it.



I am sure there are more OEM's like it,but again the point is not to go in-line pulling fuel through a in-tank pump that isn't being used.

[Project89]

but a walboro 255 or an areomotive 340lph pump in the tank

for a carbed engine a walboro 255 will support more power then u will make n/a
u will need a large return line though