Lookin for 300 HP

money maker over on this forum put out a good post. Do everything he said with some good After market heads like the edelbrock Victor JR and you will be all set.


http://www.mustangsandmore.com/ubb/Forum1/HTML/005310.html

Have you considered efi, lower compression and boost? If not, a carbed stroker could be an option. What kind of engine/cam etc. is it?

You DO NOT want vic jr heads on that car. that is WAY too much head.

I guarantee that if you swap to a set of box stock twisted wedge heads or a set of performer heads and a good cam, you will meet your 300 hp goal.

Twisted wedges are the only head you will be able to run with a 202 intake valve and not have to cut your pistons. The performers you can pick up used for less than 700.

You wont need to radical of a cam. Do you have a roller or nonroller block?

In case yea did not want to hit the link here is what I could Find on another mustang forums from a good builder over there.
This was written for a 1500 dollar budget limit for 300 horse at the fly wheel
add some good heads and I bet you get your # at the Rear Wheels.


OK, let's try this one more time. After researching several machine shops in my area I will assume that these prices can be duplicated or bettered by most of the USA membership. This build up is based on a garden variety 65-78 289 or 302 Windsor good condition donor engine core. You will need to completly dissassemble the engine. 1) Degrease and cam bearing bare block with cam bearings $95. 2) Bore .060 and finish hone $160. 3) micro polish carnk shaft $30. 4) Check connecting rods and fit piston pins $40. 5) Valve job $130 6) Mill heads .030 $60. 7) machine heads for screw in studs $80. Total spent at machine shop $595.
Parts: I opted for a PAW type of inexpensive rebuilder quality engine kit consisting of rings, bearings, oil pump, timing chain and gears, and a gasket set. These generally contain decent quality brands such as Michigan, Muskegeon, Detroit Gasket, Melling, etc. I priced mine through my normal wholesale supplier at $155. You may pay a bit more. 2) a set of Badger .060 11 to 1 pop up cast pistons from us at $150. 3) Comp 270S cam, solid lifters, and valve springs $250. 4) Steel shim head gaskets $40. 5) Edelbrock Air gap or similar intake $220. 6) A set of screw in rocker arm studs $20. 7) a set of Headman 4 tube headers $90. total of $925 in parts. Grand total of $1520 spent to get 300 horsepower at the flywheel.

If you already have headers you are money ahead. The same with an intake. 351W heads woould be a bonus and add about 20 to 25 HP stock. You will need a GOOD 600-750 max CFM carb. A 4100 series 1.12 Autolite is nice or a 700 CFM DP Holley is better. Anything in between is OK also except a Jimmy Carter POS carburrito. If that's all ya got then so be it! What ever electronic ignition you havbe (like a FoMoCo Duraspark) is fine. This engine will make 300 HP@6000 RPM at the flywheel on a dyno guranteed if assembled correctly. Does it sound familiar? Well it should as it is basically a higher compression 289 HIPO. Add a bigger carb, tube headers, an efficiant intake, more compression, more cam and you have got 25 to 30 more HP than the 271 easy. The best part is that it will last and take lots of abuse. These babies are very forgiving if the time is taken to assemble them right. Enjoy!
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You can go .030 if you like. The .060 over bore being too thin is an old wives tale. We go .070 over on 289/302 blocks all of the time on our race motors. The pistons have valve reliefs. There is no economical similar piston for a 351 unfortunatly. You will need a steady diet of 93 octane with careful timing adjustments. The 270S cam will allow the high compression. Loosing 2 full points will cost you 25 horsepower


Alex Denysenko
Co-Administrator and Moderator
NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00 & '01
Fleet of FoMoCo products

you wont be able to run the RPM heads with stock pistons.

Figuring 30% power loss from tranny and accessories 300rwhp is around 430 at the flywheel. Is this too much to ask of a street driven 289 running on pump gas? What if you stroked it out to 331 or 347?

what kind of math is that? Unless you have a really tight C6 and tight rear axle, you shouldn't be getting 30% loss. Of course 300 at the wheels with 430 at the fly is a bit more than 30% loss anyway. You really only need about 360hp at the fly to get 300 at the wheels. With traction, most people would be surprised what a 300 hp(at the fly) 302 can do in a early mustang.

I read in the thread linked above that you should figure 20% loss for a manual and 30% loss for an auto. 300rwhp with a 30% loss works out to 428.571 at the flywheel, I rounded up

What would you reccomend?

gt/cs said:

I read in the thread linked above that you should figure 20% loss for a manual and 30% loss for an auto. 300rwhp with a 30% loss works out to 428.571 at the flywheel, I rounded up

Click to expand...

30% sounds way too pessimistic to me. I'm figuring on 15%. I'm doing this exercise with a 5.0L EFI conversion into a '67 XR-7 Cougar. After I add up all the HP gains from one mod, or another, I'll have about 350 HP at the flywheel. With an AOD, I expect somewhere around 300 RWHP.

Steve C.

gt/cs said:

I read in the thread linked above that you should figure 20% loss for a manual and 30% loss for an auto. 300rwhp with a 30% loss works out to 428.571 at the flywheel, I rounded up

What would you reccomend?

Click to expand...

I guess it depends on how you look at it, 300 at the rear plus 30% gives you 390 at the fly. But, like you said, take 30% from 430 and you get 300. Regardless of whether its 90 or 128.xx hp, you're just not going to lose that much through a properly setup drivetrain in an early mustang.

30% of RWHP is NOT 30% loss. It is 30% of (FWHP - LOSS)

To work it out, from engine HP, you subract your loss from 100% and multiply by the remaining to get your RWHP after loss like: 400 * ((100 - 30) / 100)

= 400 * 0.7

So to get from RWHP to FWHP, you divide by 0.7 or 70% This is essentially like multiplying by 1/0.7 which is like multiplying by 1.42....

A certain percentage of a big number is going to be a bigger percentage of a smaller number.

1967 coupe-no, use a 302 or 289 intake

Route666, thanks but I don't need a math lesson. The previous post was an attempt to figure how a 430 horse engine only puts 300 to the wheels. I can see how my wording could have come across as flawed logic in my first post, adding 30% to rear wheel numbers does not a flywheel number make. My point was that you either have a 430 horse engine or 300 rwhp, can't have both. The only vehicles that have that kind of loss are big 4WD trucks with big tires and a dragging e-brake. Early mustangs should not have 30% loss unless something is damaged or way out of adjustment. 30% is a number magazines use to promote their advertisers products. The added drivetrain loss is used to inflate increases of the manufacturers parts, and normally they can get away with it because they don't do a baseline pull or don't follow a standard testing routine. Anyway......

If you have a C4, just multiply your horses at the fly by .80, if you have a manual trans., multiply by .82. If you have a C6, multiply by .77-.75 to get power at the wheels.

Generally:
Manual tranny: 12-20%
Auto tranny: 18-25%

There are exceptions and reasons for variation...
ie:
C6 tranny eats up ALOT of power.
Aluminum or CF driveshaft will put you on the low end of the scale.
9" rear eats up a little more power than 8".
Etc...
The T5 is a more effiecent tranny than the T/C, so it is on the lower end.
If you notice, lower power loss parts are weaker though, so there is a price.
8" rear
aluminum shaft
C4 or T5
etc...

Btw: Stock heads with minor work will support 300 rwhp.
Dave