On the way GT40 heads and Explorer intake!

[MY 85 GT]

Ok i bought a set of GT40 heads and a Explorer intake and a set of 1.72 frpp roller rockers..My question is how much over stock will the motor rev to now...compared to the stock set-up?...Also what type of HP will i make...This car has a Paxton SN93 blower making 6 psi..Hoping for more boost with a UPR powerpipe....im converting it to MAF it will have a 77mm C&L Meter...70mm TB..24lb injectors...FMU also....adjustable fuel pressure regulator..It has BBK shorties...I might go with an off orad X or H pipe and a Mac cat back...it will have 3.73's and its an AOD with a wicked shift kit..too....what type Of ET's should i run and any estimate on RWHP..thanks...

 

[lancec2c30]

What valve springs are in the GT40's? If they are stock, you prolly won't be revving any higher at all.

 

[MY 85 GT]

What valve springs are in the GT40's? If they are stock, you prolly won't be revving any higher at all.

Im sure there stock valve springs...What springs should i install?...

 

[stykthyn]

trick flow gt40 upgrade springs. stock exploder springs wont hold up to even a stock HO cam

 

[MY 85 GT]

trick flow gt40 upgrade springs. stock exploder springs wont hold up to even a stock HO cam

Ok can i do that myself?...or the shop that doing the install can they do it?...were can i get that?...summit? or Jegs?

 

[stykthyn]

summit has them.

 

[lancec2c30]

This would be the spring kit. I think most people will agree that if you have any mechanical experience at all you should be able to do this pretty easily. Just rent the spring tool from autozone.

Trick Flow Specialties TFS-2500100 - Trick Flow® Valve Spring Upgrade Kits - Overview - SummitRacing.com

 

[stykthyn]

even with all the new equipment you arent going to rev any higher than it would before. there is more to spinning your motor to the moon than putting on new heads/intake.

after saying that you should see a nice bump in power especially with the blower. you might even see an extra couple of psi b/c the engine can breath easier.

 

[Mustang5L5]

You still have the factory bottom end...so your rev limit will not increase.

 

[MY 85 GT]

Ok i can deal with that so wonder were the car will make power then 5000 rpms or so...Wonder what type of RWHP i will have?

 

[fiveohwblow]

Well when I put my heads on I actually saw boost decrease. Think of the engine as a giant air pump. You put a bigger hole on either end of the pump, pressure inside the pump decreases.

That being said, a drop in boost does not equate to a drop in HP, but in your case the opposite. I know what question you were asking as far as the revvs. When I put my h/c on my car I noticed I was good until 6k instead of the measly 4800-5k with stock. Especially since you will have the supercharger spinning centrifugally.

My guestimate is somewhere in the lower to mid 12's say 12.5 or 12.4.

Good luck and keep us posted!

Edit: Its hard to get accurate numbers with an aod on the dyno but I would say mid 300's. I had my 5 spd on the dyno with all stock h/c and cobra intake and similar other boltons and spun to 296. With your heads, intake and power pipe (gave me 1.5 lbs) I would hope you would gain at least 30-40 rwhp over what I had.

 

[MY 85 GT]

Thanks guys talked to the shop today thats doing my car I told him i bought GT40 heads he TOLD me that he will send them out for a 5 Angle valve job,port and polish and to install the TFS spring upgrade kit..I wonder will that help with HP a little i know its a good idea to have the heads re-done/checked anyways....Also i have to upgrade the fuel system now to 255 lph fuel pump is a good idea im sure? Im running 24lb injectors with an FMU and a adjustable fuel pressure regulator..what else do you think i need?...Oh yeah it has a BBK 70mm TB and a C&L 77mm MAF meter too...

 

[stykthyn]

my .02 cents says dont bother with porting or doing a valve job. clean them up and slap them on the car. for the money you are going yo have in those heads you could almost get a set of aluminums that will outflow and weigh less.

 

[fiveohwblow]

Agreed with styk unless you are getting a phenom deal. Also, I would suggest ditching the FMU and going with at least 30 lb injectors. Trust me I have my FMU sitting in my garage cause I am almost not willing to sell it to anyone else. Although mine worked for me, I dont want to trust a diaphragm to ensure proper fuel delivery. I have since stepped up to flow matched 42 lb'ers. When I was running your combo I had 30's and they were almost maxed. The 255 supports my current power levels which are above what I suspect yours will end up being (compliments of 13 lbs of boost) so that pump should be adequate. If you are going Walbro check on the specifics as they make a standard and hi-po 255 pump, obviously I recommend the hi-po

 

[MY 85 GT]

Stupid Question..what spark plugs does the GT40 heads take are they the same as the stock heads?....if not does anyone know the part number for the GT40 heads...

 

[Mustang5L5]

Same as 1993-1995 Cobra.

 

[fivespeedsteed]

gt40-ps will take normal 5.0 headers right? im helping my friend with his truck

 

[stykthyn]

they will, but you will have a hard time getting your spark plugs on and off

 

[82CapriRS]

unless you got ford headers, atleast from what i read anyways.

 

[88blowngt]

Go with BBK shorties or MAC Longtubes for spark plug clearance.