I was out in my shop a while back and thought why don't I modify my intake on my 85GT to take a larger Throttle body and fix the choke spots in these factory intakes. I already increased from 52mm stock Holley TB to a 54mm Bosch Motorsports TB. But as we all know bigger' faster, better. I was having problems posting this thread and will try to post this before continuing
Yahoo It finally worked. So I started by searching for a donor upper manifold and thanks to Tristen who went to a lot of trouble to get it shipped to me I now had a base to work from. This is my original intake on the car
and this is the donor manifold So first I built an adaptor plate to fit my new 60mm Bosch Motorsport TB. cut out of 1/2" aluminum plate. Then I built a jig to hold everything in place for fitting and welding. you can see her how big the new TB is compared to the original mounting plate. And then I took my grinder with a zip blade and cut the manifold apart retaining the bottom of the inlet runner to keep the EGR port which I use for my Bosch MAP sensor Sorry I have run out of time to finish this but will continue soon
And yes Patrick I will finish this. surprised that you would be interested in this mod.
I'm surprised you're surprised!
I've long been aware of the bottleneck in the factory intake. It was a local club member who came up with the original DAWG modification years ago. I've always been interested in seeing how this restriction has been overcome.
Yes I've seen the dog mod and I am sure it works for the squashed area where the pipe meets the plenum. I am addressing that and more. My goal was to get rid of the 120 degree bend for the #6 intake runner. sorry I got the photos mixed up. The one photo show some of the fitment work on the pipe. The first picture I circled the bad corner into #6. I bought a new TIG welder and it has some different procedures compared to what i am used to so it took some serious practice to get some decent welds as this next photo shows. It took quite a while to do all the fitting and welding as there were 11 pieces all together. I did some tapering and polishing to blend the mounting plate to the pipe and ground all the factory flashing lines and polished the whole exterior. I cleaned inside and out and prepped it for paint. Here is a tip for you I use VHT caliper red paint . It is as tough a paint as you can find the colour is as close to perfect match as you can get and gas and oil don't bother it. And here I am checking the fit of the 60mm TB [img]https://images.fiero.nl/userimages/sleek%2520fiero/IMG_4549.jpg[/img I will post more when I install it. I am also going to do the cold air pipe in the wheel well. My air cleaner housing has been modified on the outlet already and a K&N filter installed.
Some of the pics don't come through. I'll try that last one again.
The last bracket after [/img is missing.
quote
Originally posted by sleek fiero:
Yes I've seen the dog mod and I am sure it works for the squashed area where the pipe meets the plenum. I am addressing that and more.
I believe part of his goal was to open up the restriction while retaining the factory appearance of the intake when viewed after installation (good for collector plates)... but yeah, no doubt the air flow can be improved upon even further.
CLICK FOR FULL SIZE
With your reassembled/modified intake, were you able to smooth out the interior passages where the added material was added/welded?
[This message has been edited by Patrick (edited 12-12-2023).]
Yes the interior is pretty clean. I had one "grape" in the neck which was easy to reach with my die grinder. The rest I could inspect with my bore scope and it looks good. I was very careful to keep the weld penetration to a minimum. By the way it isn't #6 intake runner that got opened up 'it was actually #3 runner. That was the most important change as the corner was so sharp. sleek
Hi Patrick; that's where I went wrong as well. #6 cylinder is there But that runner actually crosses over to #3 through the middle and lower manifold sections.
Ah, I understand now. Yes, it's easy to forget that the numbering of the cylinders doesn't actually match the layout of the upper intake (and the runners that feed them).
So correct me if I'm wrong, but it would appear then that you took some of the sharpness out of the turn in this runner's pathway?
[This message has been edited by Patrick (edited 12-12-2023).]
Hi Da; I haven't really talked about it yet as everytime I mentioned it someone would have something negative to say about DBW. But yes I am running an Emtron ecu and Bosch components. I don't want to change the subject matter of this thread so if you want to talk about it more probably we should go to general Fiero chat
Notorio; I think if a person spent a little more time than I did nobody would notice and if your car would pass the smog test before I don't think anything would change with this mod. It's just making more air available. I'm going to post a few more pictures as I'm removing the air intake muffler in the wheelwell and modifying my air cleaner housing to remove another restriction and still have it look stock.
In my original 187 rwhp Fiero intake, I shortened/shave the space between the upper and middle intakes which in effect opened up that transition area where they meet. In another intake I simply bored the inner side about 3/16" on both upper and middle. You need to cut the gasket to match.
I recently saw another mod that had the pipe from the TB flared out, fairly closely behind the throttle body. The "corner" that you radiused was almost completely removed on that version. The opening from the neck into the plenum was a large oval - almost a rectangle. Took up probably 2/3 of that end of the plenum.
so I got a foot of 3" pipe and had it bent a few degrees. Then I cut ,fit and welded until I got the right shape. I used the old Muffler mount and welded it in place and installed back in the wheelwell
I already have a side scoop I built before so now when warm weather comes we will see if these mods were worthwhile. sleek
I finally installed the modified intake manifold and 60 mm Bosch Motorsport throttle body. It starts and runs well but I will wait until nice weather to take it out and do some datalogging. Everything fit well and looks good. One more project off my plate.
[This message has been edited by sleek fiero (edited 01-28-2024).]
This is good work. Before I went down the 3800 engine swap route, I did a similar mod to my original intake. Lots of aluminium welding!
(There were 2.8L GM V6's that could put out 300HP for racing purposes. I was going to try to copy some of the ideas at the time... ....But I went turbo and the easier route!)
Regards, Rafe
[This message has been edited by Frenchrafe (edited 01-29-2024).]
This is good work. Before I went down the 3800 engine swap route, I did a similar mod to my original intake. Lots of aluminium welding!
(There were 2.8L GM V6's that could put out 300HP for racing purposes. I was going to try to copy some of the ideas at the time... ....But I went turbo and the easier route!)
Regards, Rafe
I did that too, spent years and many dollar on 2.8's only to realize the gains are ever so minimal, insignificant....I did it all, cylinder boring, cams, intakes, headers, tuning and the gains were questionable....
300 hp out of a 2.8? i'm gonna call that now. Suuuure you can spray that thing too death, anything can make 300 hp once
[This message has been edited by jelly2m8 (edited 01-29-2024).]
I'm talking about the all aluminium racing block that GM produced for competition purposes. The intake was like a high perf carb intake on a V8. It breathed well and could maintain quite high revs. But like I said, it was for competition only, but you could buy a block in 1981 and build it up for your race car! I used to have the docs and specs.... ...there were good infos that could have been adapted to the iron block.
------------------ "Turbo Slug" - '87 Fiero GT. 3800 turbo. - The fastest Fiero in France! @turboslugfiero https://youtu.be/hUzOAeyWLfM
Originally posted by Frenchrafe:I'm talking about the all aluminium racing block that GM produced for competition purposes. The intake was like a high perf carb intake on a V8. It breathed well and could maintain quite high revs. But like I said, it was for competition only, but you could buy a block in 1981 and build it up for your race car! I used to have the docs and specs.... ...there were good infos that could have been adapted to the iron block.
Yes! I remember that engine! It was a GM crate motor that you could buy. It was actually an all aluminum 3.4 short block, and it was pre-drilled for both start locations.
GM Performance Parts offered a high performance crate version of this which had a wild cam, an aftermarket intake, and was carbureted. It was meant for circle track racing.
But here's another thing... and I kick myself repeatedly for not having bought them when I saw them. GM ALSO made a VERY short run of aftermarket "GEN-1" High Performance all aluminum cyl heads. YES. Every time I mention it, people correct me and say that they were for the newer Gen-2 V6/60, and I correct them. GM literally made a short run of 50 sets of aluminum Gen-1 cyl heads... essentially the same specifications as the ones that were on the Pontiac Fiero (considered the HO version of the gen-1 cast iron heads). I saw a set, un-machined (hadn't had valves installed yet or studs installed) on eBay, and they sold for $250 bucks. This was back in the mid 2000s. At the time, I could have afforded it, but I decided against it because I didn't want to spend the money. I kick myself now... but whatever. I'll survive.
I don't really know what difference it would make. But you'd have a combined ~65 less pounds in the rear of the Fiero with an all aluminum Gen-1 V6/60. Which... as I type that out now... it doesn't seem so significant, haha...
Yes! I remember that engine! It was a GM crate motor that you could buy. It was actually an all aluminum 3.4 short block, and it was pre-drilled for both start locations.
GM Performance Parts offered a high performance crate version of this which had a wild cam, an aftermarket intake, and was carbureted. It was meant for circle track racing.
But here's another thing... and I kick myself repeatedly for not having bought them when I saw them. GM ALSO made a VERY short run of aftermarket "GEN-1" High Performance all aluminum cyl heads. YES. Every time I mention it, people correct me and say that they were for the newer Gen-2 V6/60, and I correct them. GM literally made a short run of 50 sets of aluminum Gen-1 cyl heads... essentially the same specifications as the ones that were on the Pontiac Fiero (considered the HO version of the gen-1 cast iron heads). I saw a set, un-machined (hadn't had valves installed yet or studs installed) on eBay, and they sold for $250 bucks. This was back in the mid 2000s. At the time, I could have afforded it, but I decided against it because I didn't want to spend the money. I kick myself now... but whatever. I'll survive.
I don't really know what difference it would make. But you'd have a combined ~65 less pounds in the rear of the Fiero with an all aluminum Gen-1 V6/60. Which... as I type that out now... it doesn't seem so significant, haha...
Makes me wonder where all these engines and heads are today ...
I finally installed the modified intake manifold and 60 mm Bosch Motorsport throttle body. It starts and runs well but I will wait until nice weather to take it out and do some datalogging. Everything fit well and looks good. One more project off my plate.
That looks gorgeous! Well done!! It's been an entire day and we are waiting for your performance report ...
[This message has been edited by Notorio (edited 01-30-2024).]
Makes me wonder where all these engines and heads are today ...
Yeah... I check "the eBays" every so often, but I see them less and less. There was a lot of discussion about those aluminum heads like 15 years ago, but after seeing them on eBay when I did... I haven't seen them since. I have to assume most of them were purchased for dirt track racers since that seemed to be the primary market for them.
Really though, the engine doesn't make a whole lot of sense unless you're looking to build a super expensive all-stock looking Fiero that's not numbers matching... getting the lowest weight you can with the maximum power possible in stockish form. For anyone that would want this engine to just increase horsepower though... the newer V6/60s are just so much better anyway.
But not going to lie... if I saw those Gen-1 aluminum heads for sale, I'd buy those suckers right now.
It's a big place. Warm and wet on the south coast, colder inland (and farther north). It was up to 18°C (64.4°F) this week. Not bad for January in The Great White North!
It's a big place. Warm and wet on the south coast, colder inland (and farther north). It was up to 18°C (64.4°F) this week. Not bad for January in The Great White North!
Victoria is quite mild, much the same (if not more so) than Vancouver. The red dot on the map indicates where Victoria is. There's a lot of BC inland and to the north. The weather/climate can be quite different depending on where one is located in the province.
I finally installed the modified intake manifold and 60 mm Bosch Motorsport throttle body. It starts and runs well but I will wait until nice weather to take it out and do some datalogging. Everything fit well and looks good. One more project off my plate.
...
