Why Are HotAir Cars Slow?

[boostmaster]

You can put turbos capable of mid 10s on the hotairs.... I'm running one.

Ported gutted intake flows more than a stock 87.

Yes it does but a properly ported stocker will flow at at least equal to the stock 87.

Problem is you can push more air through a given opening than you can suck.

True but you will gain more from a ported throttle body on a hot air than on an intercooled car because of this flaw. The draw through design does have its setbacks.

It's about pressure ratio. Any restriction on the intake side of the turbo has a huge effect on the outlet temps. That TB mounted on the inlet side of the turbo hurts the hotairs-- especially modded hotairs more than you think, including spool and power.

100% agree with all these statements. More boost, more pressure, more heat. No time for that hot discharge air to cool since it's going strait into the intake. That's why we spray alky after the turbo adapter.

Bottom line is IMO the only reason we don't see more hot airs at least in the 11's is a lack of tuning experience and impatience. I think this will be the year a few people on this board will reach that goal.

 

[BRAD_PADGETT]

00% agree with all these statements. More boost, more pressure, more heat. No time for that hot discharge air to cool since it's going strait into the intake. That's why we spray alky after the turbo adapter.

Bottom line is IMO the only reason we don't see more hot airs at least in the 11's is a lack of tuning experience and impatience. I think this will be the year a few people on this board will reach that goal.[/QUOTE]

The above comment is correct IMO but it won't be me who will do it. My car runs fine and the ported stock heads and intake work fine for my goals-mid twelves. I am slowly working on the 3 inch downpipe for our cars along with a fellow TTA member. Brad

 

[Jerryl]

What is really funny, is that at times, you see members (99.99999% are OEM IC’d cars) who have impressive numbers in their sigs , like “10.XXX @12X”, and, wonder how you detect an exhaust/vac leak, or how to set the TPS. YES, we ALL started somewhere and we all have questions. I am not slamming anyone, so read on.

I keep telling my buddy that a HA would not “put up with ½ the S*** tune” his IC car will run at (and sound good running it), as a HA is not very forgiving in the tuning area. I am FAR from a “know it all”, but it just shows how forgiving the IC cars are with the tune . These IC'd cars just flat out run with a 1/2 @$$ tune ……….. We should all try to spend less $ on parts, spend more time/$ on engine management and continually strive to max out our combo! :biggrin:

Eidt:
Maybe we should define "Max out your combo"??????

 

[boostmaster]

I keep telling my buddy that a HA would not “put up with ½ the S*** tune” his IC car will run at (and sound good running it), as a HA is not very forgiving in the tuning area. I am FAR from a “know it all”, but it just shows how forgiving the IC cars are with the tune . These IC'd cars just flat out run with a 1/2 @$$ tune ……….. We should all try to spend less $ on parts, spend more time/$ on engine management and continually strive to max out our combo! :biggrin:

Eidt:
Maybe we should define "Max out your combo"??????

Funny I made the same exact statement some time ago in a thread. You wanna know why the 86-87's are easier to tune???? Here is the answer. Cool84 mentioned this earlier, the draw through design is very inefficeint and it takes much more air to make power with this design. Eveyone is trying to figure out what the magic bullet is with the hot airs and this is it. Think of it this way, if you have glass of water it is much easier to damn near blow all the water out of the glass through a straw than to suck it through. The same applies to our turbo intake design that's why it will take a much larger turbo for the hot air compaired to the intercooled cars to get the same results. Since the draw through design is so inefficeint a much larger turbo is needed to pull the extra air required to compensate for the design flaw. The intercooled cars don't have to overcome this problem and since their design is much better it easier to overcome tuning errors. Which in part is only boost, fuel, timing. That is also why a ported throttle body gets better results on a hot air vs a intercooled car. Add the supported mods necessary to overcome this flaw making it easier to pull more air ( super big turbo, cam , heads) and you are there 11's all day long. You don't necessarily need the super big turbo but the larger the housing the less heat it will create and with the matching set of heads you could run low boost and make power.

 

[cwmccray]

I agree 1000% with all the statement. Lee Thompson was and still is a valuable source. He now can probably tune a intercooled car better than most. He got a Hot Air in the mid 10's. There were not alot of parts available. I was hoping Leeo would get into the 9's first. I can only guess that he was ready to move on. Brent and Jerryl and others (Jamie, turbo6x2) can take up were he left off. I have LEARNED alot with my car. I plan to take my car as far as it will go. I have a 87 intake that will eliminate the HOT AIR issues and will be porting my 8442 heads. I plan to see what will work and what won't. I have the JS manufactoring style pipes to take it from Hot Air to intercooled. I going to add alky and nitrous. For me to do all of this TUNING will be very VERY VERY critical . I am a Buick nut... I really like the work Bruce did with his 87 GN and he took off his intercooler and added alky. I really would like to see Brent hit the 11's and then the 10's, if TURBO6X2 (Ms. Jamie) don't hit it first. COOL84 has had a KILLER combo that I liked. I just want to get my car similiar and be able to go from HOT to COOLED in ten minutes

 

[Jerryl]

Sorry fella's ..... I was driving around today while thinking.

One other advantage the IC cars have is timing. Sure they can do that because of the IC, but in theory, a HA at lower boost levels, should be able to run high timing.

So, what about running low boost (in the turbo's sweet spot) and start increasing timing. Of course, you need to stay around 11.5:1, so you need to pull fuel, add meth, increase timing. If you get KR, spray more meth, pull fuel ...... keep doing that untill you find the max your car likes. It will be interesting to see if you can get a HA on 93 and meth in the 22- 24 deg timing range. (Should not be an issue, theoretically )

Edit
I realize this issue has been covered MANY times and there is extensive input on this on the board.
I also think that in he past, the adjustability of timing and control of the alky was simply not as good as it is today. That being said, it may be another story in today's tuning world with the updated "stuff".

 

[WFO]

Bottom line is IMO the only reason we don't see more hot airs at least in the 11's is a lack of tuning experience and impatience.

Don't forget lack of traction. :biggrin:

As far as tuning goes,I can't think of many hotair cars running maxeffort chips even though I've been harping about them for years.The tunability of those chips is amazing if you're willing to take the time to learn them.

IMO you should have your tune 90% worked out by street driving.By the time you make it to the track you should only have small changes to make as you crank the boost/timing.That saves lots of time and effort and wasted shakedown passes.

Hell,if I recall correctly my car went around 110mph right off the street on 19#,from there I just crept up on the boost and watched the knock light.

 

[JOELO'S T-TYPE]

And I ask, why not try stand alone engine management? There are plenty of options out there.

 

[Jerryl]

......... Hell,if I recall correctly my car went around 110mph right off the street on 19#,from there I just crept up on the boost and watched the knock light.

What was the combo on that run, i.e. Turbo, timing, cam, porting, exhaust, octane?

 

[bison]

I havent tuned an 84-85 in nearly 10 years . But back when i did i was able to get a lot more than most with simple tuning. I didnt even have a scan tool at the time so i simply tapped the O2 circuit to get a little edge on tuning. With all the sensors set and the boost set at 15psi the car picked up tremendously over stock. I considered the restriction on the turbo inlet but came to the conclusion that its not as much of a restriction as one would think. I could see it being a small problem at 400hp and much worse trying to obtain higher numbers. Has anyone tapped and installed vacuum guage before the compressor inlet and after the TB? I think the flow on turbos is calculated at .5psi pressure drop. This would give some real answers and let us know exactly how much the TB is restricing mass flow at different hp levels. I recently dynoed my 86 car and it did 559 to the wheels with the stock MAFS minus 1 screen. The vacuum created between the turbo and MAFS was enough to actualy start to pull the hose toward the compressor inlet. It would spring back when leting off. Do i think it would pick up 60-70hp removing the restricion with the t72 in after it? No way. Maybe 30-40 hp if im lucky. I actually wanted to see what i could get with the stock MAFS on it for comparison to some of the other heavily modded engines without the restriciton. For the 84-85's i would be most concerened with the intake manifold and exhaust flow manifold flow.

 

[WFO]

What was the combo on that run, i.e. Turbo, timing, cam, porting, exhaust, octane?

TA-61
Port matched heads and intake
Spearco frontmount
MM 208 cam
LT headers/3" DP,ATR 3" single
42# injectors,16 pos. Maxeffort chip
3200 stall 9/11 convertor

Was running C16/pump gas mix with 24* and ~25psi.Couldn't hook for sh!t on BFG drag radials.

Man,that was a while ago.Looks like everyone forgot about me already .

http://www.turbobuick.com/forums/hot-air-non-intercooled-tech/130504-couldnt-buy-11-weekend.html

 

[MoeJr]

WFO I was under the impression that the mph you quoted was for a hotair. I think that is what the original poster was looking for was time on a HA. U added an intercooler so that makes a difference.

 

[WFO]

Ok.

 

[Boost231]

well

well i hope to have my car toghter soon. i talked to nick micale yesterday and were going with a set of killer iron heads. im going to get the intake ported matched and a few other things but im going to keep the stock came. im sure 11's will be in my near future.

 

[MoeJr]

Boost 231 there is one other thing that may help you go a bit faster. Get rid of those lard a** 87 GN rims. Those things have got to be the heaviest steel rims on a car that I have ever picked up. When I changed the rims on my old 87 GN to aluminum I couldn't believe the difference in weight. I am not exaggerating when I say I bet you could shave 50-75 lbs just changing those rims.

 

[Boost231]

true

i would agree with you but i like the look of those rims.

 

[WFO]

WFO I was under the impression that the mph you quoted was for a hotair. I think that is what the original poster was looking for was time on a HA. U added an intercooler so that makes a difference.

Now that I've got a second I thought I'd point out that Razor's alky kit can be worth the same amount of power as an intercooler.Lee Thompson proved that years ago,and if I'm not mistaken Cal had some good results swapping his I/C for alky.

Anyway,back on topic.

Ported heads are a great idea,and if I was gonna pull the motor down that far I'd put in a cam for sure.Lee would do the same .

 

[boostmaster]

Man,that was a while ago.Looks like everyone forgot about me already .

I did'nt forget, glad to see you back. That was back in the days when this board was alive with real racers. Lots of r&d and useful info to pass around back then. This just aint the same ole board anymore. I still hold out hope for a resurection.

 

[Boost231]

y?

why would you put a cam in at this piont? that means i have to pull the front cover and what not. i always can pull the intake off later and do a cam but a cam is not going to help much i dont think please let me know your thoughts

 

[Jerryl]

why would you put a cam in at this piont? that means i have to pull the front cover and what not. i always can pull the intake off later and do a cam but a cam is not going to help much i dont think please let me know your thoughts

Not suggesting you put a cam in, just trying to answer the "big cam" question. Read Lee's advice in the thread.

http://www.turbobuick.com/forums/ho...ch/8447-how-much-too-much.html?highlight=hood