H.O. Upper stuff swap on LoPo - Does this produce noticable gains?

[DerekTheGreat]

Hey hey,

I was reading through Dave's Brown Blob page and noticed in the beginning he swapped out the LoPo upper intake and related stuff for HO goodies. Aside from a high idle it appeared to work although the throttle body he used looked huge... Has anyone else ever done this? Would you recommend it for those who'd like to keep their factory block?

Cheers,

Derek

[pantera77]

HO upper intake, HO Throttle Body, and stock EGR spacer bored to 63 mm is a very common mod, and IMO one of the first things you should do.

Now if your taking about a full HO converted lopo, that's also a common swap. There's no difference between a HO short block and a lopo short block, other then the HO has nice forged flattop pistons and the lopos have crappy dished cast aluminum ones.

[DerekTheGreat]

Cool, so the computer doesn't mind the changes? Dave reported better grunt around town and less effort to maintain 90mph, which is exactly what I'm looking for. This sounds like something I could do myself in an evening, very appealing. Why does the spacer need to be bored out? I don't have access to that type of equipment nor do I know anyone who could do that. If Dave chimes in he could say what TB he used and what exactly was done to the hole on the butterfly to get his idle to calm down..

I'd like to just swap a complete HO in but finding a nice looking motor around here for cheap isn't likely.. It seems with the upper swap hope for more power is not lost!

[pantera77]

For just the intake, the computer doesn't care. Full HO conversion it would obviously need to be a HO computer.

The stock EGR spacer opening is really puny, it would be a choke point. I used a regular HO TB on two of my cars, and a Explorer TB on another (since it's what I had laying around). The Explorer one is a little bigger, IIRC it's ~65mm, HO is ~60mm, and lopo is ~50mm. Both worked fine, I never had any idle problems. You do need to swap the TB linkage with the stock box one.

HO upper, Bored EGR spacer, HO TB vs. stock lopo bits

[DerekTheGreat]

Thanks for the post, it's neat being able to see LoPo & HO stuff side by side!
That big throttle body, is that the exploader TB or regular HO one? Glad to know stock computer won't have issues and so if all I need is the EGR spacer I best get my butt over to the for sale or wanted section.

What kind of difference did you notice after the swap?

[pantera77]

The "big" TB is just a stock HO one. The stock lopo one is laughably tiny.

The biggest difference is the throttle response. It's much nicer.
HP wise, it may be worth 10 at the crank. My old bone stock 91 GM went from an 11.53 to a 11.39 in the 1/8th from nothing but this. (yes that car was awfully slow)

[HiFiMerc]

I'm running an HO upper on my '90, with an Exploder TB and bored out EGR spacer. As mentioned, it seemed to help with throttle response. I didn't have any issues with anything either. It does idle a bit high or so when first started (about 1500), probably related to the bigger air hole on the 65mm TB.

Along with duals, it's a noticeable difference over the standard intake and single exhaust.

BTW, you might need a 3/8" spacer to mount the HO intake when using the stock fuel rails. Mine only needed about an 1/8" but I don't think you can get them that short.

[87gtVIC]

I believe it was an explorer throttle body Scott modified for my car.

I put a plug in the hole (the plastic type you put into brick and drive a screw into) and it was the perfect piece to make the idle normal.


Thank you for reading my thread.

[85crownHPP]

We actually dyno'd my '85 (converted to SEFI/HO upperstuff) and Scott B.'s stock 89, I had a whole 10hp more at the wheels I may have done a little better if it wasn't burning so much oil
We both have similar dual exhaust with stock 5.0 mustang exhaust manifolds.
When I swapped I was coming from CFI so I noticed a lot more difference than others, of course...! I did still think it was a little peppier than my '91, which I have since also put HO upperstuff onto.

[DerekTheGreat]

I'm running an HO upper on my '90, with an Exploder TB and bored out EGR spacer. As mentioned, it seemed to help with throttle response. I didn't have any issues with anything either. It does idle a bit high or so when first started (about 1500), probably related to the bigger air hole on the 65mm TB.

Along with duals, it's a noticeable difference over the standard intake and single exhaust.

BTW, you might need a 3/8" spacer to mount the HO intake when using the stock fuel rails. Mine only needed about an 1/8" but I don't think you can get them that short.

You mean a spacer between the upper & lower intake? Would an HO fuel rail swap in or would that have to be modified? I've only got access to hand tools and no fabrication experience..

I believe it was an explorer throttle body Scott modified for my car.

I put a plug in the hole (the plastic type you put into brick and drive a screw into) and it was the perfect piece to make the idle normal.


Thank you for reading my thread.

No problem, your car is beautiful! If you ever want to sell it....
Looking at current photos it looks like you're using a different set up. Do you still have that explorer TB? Wanna sell it to me?

We actually dyno'd my '85 (converted to SEFI/HO upperstuff) and Scott B.'s stock 89, I had a whole 10hp more at the wheels I may have done a little better if it wasn't burning so much oil
We both have similar dual exhaust with stock 5.0 mustang exhaust manifolds.
When I swapped I was coming from CFI so I noticed a lot more difference than others, of course...! I did still think it was a little peppier than my '91, which I have since also put HO upperstuff onto.

10 HP at the wheels is worth it to me! You didn't end up catching the difference in torque did you? Did the CFI cars have hotter cams than the SEFI cars? Back when I had my '85 I thought about ditching the stock manifold for an entry level Edelbrock performer 4bbl manifold with the two barrel adaptor. Wasn't sure if my linkage would go back without modification and then I sold the car. Had the TB off of that thing and man, the stock intake looked so restrictive and narrow.

[DerekTheGreat]

The "big" TB is just a stock HO one. The stock lopo one is laughably tiny.

The biggest difference is the throttle response. It's much nicer.
HP wise, it may be worth 10 at the crank. My old bone stock 91 GM went from an 11.53 to a 11.39 in the 1/8th from nothing but this. (yes that car was awfully slow)

The LoPo stuff is tiny indeed, every time I look at them I'm surprised the things run at all and it's no wonder they're only rated at 150HP. I think the TB on my four banger Ranger was the same size, if not bigger haha. That's why I began to dig around, wanted to be sure I wasn't going to be made fun of for not doing a complete HO swap.

[knucklehead0202]

This is all great info as I get closer and closer to getting the box of my dreams. Quick question though. What is wrong with mustang/HO egr plates in relation to the crown vic ones? If I'm going to the trouble of changing the intake i'll probably just stick an aftermarket one on there and a 70mm TB. Is the a no-go because of egr compatibility problems?

[pantera77]

This is all great info as I get closer and closer to getting the box of my dreams. Quick question though. What is wrong with mustang/HO egr plates in relation to the crown vic ones? If I'm going to the trouble of changing the intake i'll probably just stick an aftermarket one on there and a 70mm TB. Is the a no-go because of egr compatibility problems?

The throttle cable bracket mounts to the EGR spacer, and it's completely different on Mustangs since the intake is flipped. It's not hard at all to make a bracket that will work, but most people just like having the stock one bored out since its a direct bolt on.
Honestly no need for a 70mm TB on a lopo. Mustang guys practically throw their stock TB's out, and Explorer ones are a dime a dozen.


There also should be no need for a spacer. The HO upper is the same as a lopo upper externally, all you need to do is swap over the lopo vacuum tree. On 90/91's you may need to grind a little slot under the intake plaque so the facotry solenoid bracket fits.

[85crownHPP]

10 HP at the wheels is worth it to me! You didn't end up catching the difference in torque did you? Did the CFI cars have hotter cams than the SEFI cars? Back when I had my '85 I thought about ditching the stock manifold for an entry level Edelbrock performer 4bbl manifold with the two barrel adaptor. Wasn't sure if my linkage would go back without modification and then I sold the car. Had the TB off of that thing and man, the stock intake looked so restrictive and narrow.

I forget what Mr B. had as far as torque, but mine was about dead on 150hp and 150ft/lbs at the wheels. The CFI cam is probably the same as SEFI, but my 85 came to me with a '86 roller block in it anyway (long story).
You can use your stock fuel rail and all, that is all attached to the lower intake.
All you need is the upper intake, a stock EGR spacer bored to match, and the mustang TB with a box lever swapped onto it. I betcha someone here has a bored spacer and swapped TB ready to go that they could sell... I used to until I put them on the 91, lol.

[87gtVIC]

No problem, your car is beautiful! If you ever want to sell it....
Looking at current photos it looks like you're using a different set up. Do you still have that explorer TB? Wanna sell it to me?

Same set up. I just painted it some time back.

I have stuff for sale..

http://www.grandmarq.net/vb/showthre...-Throttle-Body

The throttle body currently does not have the panther linkage on it. I am intending on painting the throttle body too. I just got back from three weeks out on the road. Just want to relax a bit before I get back into the groove of fixing thing and painting things.